diff --git a/flexmeasures/api/v3_0/assets.py b/flexmeasures/api/v3_0/assets.py
index d63bbc2dda..b2f14db488 100644
--- a/flexmeasures/api/v3_0/assets.py
+++ b/flexmeasures/api/v3_0/assets.py
@@ -47,6 +47,7 @@
     GenericAssetSchema as AssetSchema,
     GenericAssetIdField as AssetIdField,
     GenericAssetTypeSchema as AssetTypeSchema,
+    SensorsToShowSchema,
 )
 from flexmeasures.data.schemas.scheduling.storage import StorageFlexModelSchema
 from flexmeasures.data.schemas.scheduling import AssetTriggerSchema, FlexContextSchema
@@ -61,9 +62,6 @@
 )
 from flexmeasures.api.common.schemas.users import AccountIdField
 from flexmeasures.api.common.schemas.assets import default_response_fields
-from flexmeasures.utils.coding_utils import (
-    flatten_unique,
-)
 from flexmeasures.ui.utils.view_utils import clear_session, set_session_variables
 from flexmeasures.auth.policy import check_access
 from flexmeasures.data.schemas.sensors import (
@@ -896,7 +894,7 @@ def get_chart_data(self, id: int, asset: GenericAsset, **kwargs):
           tags:
             - Assets
         """
-        sensors = flatten_unique(asset.validate_sensors_to_show())
+        sensors = SensorsToShowSchema.flatten(asset.validate_sensors_to_show())
         return asset.search_beliefs(sensors=sensors, as_json=True, **kwargs)
 
     @route("/<id>/auditlog")
diff --git a/flexmeasures/conftest.py b/flexmeasures/conftest.py
index d3043286e4..f737bb4c82 100644
--- a/flexmeasures/conftest.py
+++ b/flexmeasures/conftest.py
@@ -548,6 +548,31 @@ def create_assets(
             ),
         )
         db.session.add(sensor)
+        scc_sensor = Sensor(
+            name="site-consumption-capacity",
+            generic_asset=asset,
+            event_resolution=timedelta(minutes=15),
+            unit="MW",
+        )
+        db.session.add(scc_sensor)
+        cc_sensor = Sensor(
+            name="consumption-capacity",
+            generic_asset=asset,
+            event_resolution=timedelta(minutes=15),
+            unit="MW",
+        )
+        db.session.add(cc_sensor)
+        pc_sensor = Sensor(
+            name="production-capacity",
+            generic_asset=asset,
+            event_resolution=timedelta(minutes=15),
+            unit="MW",
+        )
+        db.session.add(pc_sensor)
+        db.session.flush()  # assign sensor IDs
+        asset.flex_model["consumption-capacity"] = {"sensor": cc_sensor.id}
+        asset.flex_model["production-capacity"] = {"sensor": pc_sensor.id}
+        asset.flex_context["site-consumption-capacity"] = {"sensor": scc_sensor.id}
         assets.append(asset)
 
         # one day of test data (one complete sine curve)
diff --git a/flexmeasures/data/models/charts/belief_charts.py b/flexmeasures/data/models/charts/belief_charts.py
index e155438520..4cf882d9ee 100644
--- a/flexmeasures/data/models/charts/belief_charts.py
+++ b/flexmeasures/data/models/charts/belief_charts.py
@@ -11,7 +11,6 @@
 from flexmeasures.utils.flexmeasures_inflection import (
     capitalize,
 )
-from flexmeasures.utils.coding_utils import flatten_unique
 from flexmeasures.utils.unit_utils import find_smallest_common_unit, get_unit_dimension
 
 
@@ -499,8 +498,10 @@ def chart_for_multiple_sensors(
     combine_legend: bool = True,
     **override_chart_specs: dict,
 ):
+    from flexmeasures.data.schemas.generic_assets import SensorsToShowSchema
+
     # Determine the shared data resolution
-    all_shown_sensors = flatten_unique(sensors_to_show)
+    all_shown_sensors = SensorsToShowSchema.flatten(sensors_to_show)
     condition = list(
         sensor.event_resolution
         for sensor in all_shown_sensors
diff --git a/flexmeasures/data/models/generic_assets.py b/flexmeasures/data/models/generic_assets.py
index 46bb19383c..48072f0556 100644
--- a/flexmeasures/data/models/generic_assets.py
+++ b/flexmeasures/data/models/generic_assets.py
@@ -30,7 +30,6 @@
     CONSULTANT_ROLE,
 )
 from flexmeasures.utils import geo_utils
-from flexmeasures.utils.coding_utils import flatten_unique
 from flexmeasures.utils.time_utils import determine_minimum_resampling_resolution
 from flexmeasures.utils.unit_utils import find_smallest_common_unit
 
@@ -287,7 +286,9 @@ def validate_sensors_to_show(
 
         sensor_ids_to_show = self.sensors_to_show
         # Import the schema for validation
-        from flexmeasures.data.schemas.utils import extract_sensors_from_flex_config
+        from flexmeasures.data.schemas.generic_assets import (
+            extract_sensors_from_flex_config,
+        )
         from flexmeasures.data.schemas.generic_assets import SensorsToShowSchema
 
         sensors_to_show_schema = SensorsToShowSchema()
@@ -662,8 +663,10 @@ def chart(
         :param resolution: optionally set the resolution of data being displayed
         :returns: JSON string defining vega-lite chart specs
         """
+        from flexmeasures.data.schemas.generic_assets import SensorsToShowSchema
+
         processed_sensors_to_show = self.validate_sensors_to_show()
-        sensors = flatten_unique(processed_sensors_to_show)
+        sensors = SensorsToShowSchema.flatten(processed_sensors_to_show)
 
         for sensor in sensors:
             sensor.sensor_type = sensor.get_attribute("sensor_type", sensor.name)
@@ -1023,7 +1026,9 @@ def get_timerange(cls, sensors: list["Sensor"]) -> dict[str, datetime]:  # noqa
                       'end': datetime.datetime(2020, 12, 3, 14, 30, tzinfo=pytz.utc)
                   }
         """
-        sensor_ids = [s.id for s in flatten_unique(sensors)]
+        from flexmeasures.data.schemas.generic_assets import SensorsToShowSchema
+
+        sensor_ids = [s.id for s in SensorsToShowSchema.flatten(sensors)]
         start, end = get_timerange(sensor_ids)
         return dict(start=start, end=end)
 
diff --git a/flexmeasures/data/schemas/generic_assets.py b/flexmeasures/data/schemas/generic_assets.py
index a6e2e0b8df..472b63aafb 100644
--- a/flexmeasures/data/schemas/generic_assets.py
+++ b/flexmeasures/data/schemas/generic_assets.py
@@ -3,7 +3,7 @@
 from datetime import timedelta
 import json
 from http import HTTPStatus
-from typing import Any
+from typing import Any, TYPE_CHECKING
 
 from flask import abort
 from marshmallow import validates, ValidationError, fields, validates_schema
@@ -11,7 +11,8 @@
 from flask_security import current_user
 from sqlalchemy import select
 
-
+if TYPE_CHECKING:
+    from flexmeasures import Sensor
 from flexmeasures.data import ma, db
 from flexmeasures.data.models.user import Account
 from flexmeasures.data.models.generic_assets import GenericAsset, GenericAssetType
@@ -21,7 +22,6 @@
 from flexmeasures.data.schemas.utils import (
     FMValidationError,
     MarshmallowClickMixin,
-    extract_sensors_from_flex_config,
 )
 from flexmeasures.auth.policy import user_has_admin_access
 from flexmeasures.cli import is_running as running_as_cli
@@ -211,23 +211,34 @@ def _validate_flex_config_field_is_valid_choice(
                 )
 
     @classmethod
-    def flatten(cls, nested_list) -> list[int]:
+    def flatten(cls, nested_list: list) -> list[int] | list[Sensor]:
         """
-        Flatten a nested list of sensors or sensor dictionaries into a unique list of sensor IDs.
-
-        This method processes the following formats, for each of the entries of the nested list:
-        - A list of sensor IDs: `[1, 2, 3]`
-        - A list of dictionaries where each dictionary contains a `sensors` list, a `sensor` key or a `plots` key
-        `[{"title": "Temperature", "sensors": [1, 2]}, {"title": "Pressure", "sensor": 3},  {"title": "Pressure", "plots": [{"sensor": 4}, {"sensors": [5,6]}]}]`
-        - Mixed formats: `[{"title": "Temperature", "sensors": [1, 2]}, {"title": "Pressure", "sensor": 3}, 4, 5, 1]`
-
-        It extracts all sensor IDs, removes duplicates, and returns a flattened list of unique sensor IDs.
-
-        Args:
-            nested_list (list): A list containing sensor IDs, or dictionaries with `sensors` or `sensor` keys.
-
-        Returns:
-            list: A unique list of sensor IDs.
+        Flatten a nested list of sensor IDs into a unique list. Also works for Sensor objects.
+
+        This method processes the following formats for each entry in the list:
+        1. A single sensor ID:
+           `3`
+        2. A list of sensor IDs:
+           `[1, 2]`
+        3. A dictionary with a `sensor` key:
+           `{"sensor": 3}`
+        4. A dictionary with a `sensors` key:
+           `{"sensors": [1, 2]}`
+        5. A dictionary with a `plots` key, containing a list of dictionaries,
+           each with a `sensor` or `sensors` key:
+           `{"plots": [{"sensor": 4}, {"sensors": [5, 6]}]}`
+        6. A dictionary under the `plots` key containing the `asset` key together with a `flex-model` or `flex-context` key,
+           containing a field name or a list of field names:
+            `{"plots": [{"asset": 100, "flex-model": ["consumption-capacity", "production-capacity"], "flex-context": "site-power-capacity"}}`
+        7. Mixed formats:
+           `[{"title": "Temperature", "sensors": [1, 2]}, {"title": "Pressure", "sensor": 3},  {"title": "Pressure", "plots": [{"sensor": 4}, {"sensors": [5, 6]}]}]`
+
+        Example:
+        >>> SensorsToShowSchema.flatten([1, [2, 20, 6], 10, [6, 2], {"title": None,"sensors": [10, 15]}, 15, {"plots": [{"sensor": 1}, {"sensors": [20, 8]}]}])
+        [1, 2, 20, 6, 10, 15, 8]
+
+        :param nested_list: A list containing sensor IDs, or dictionaries with `sensors` or `sensor` keys.
+        :returns:           A unique list of sensor IDs, or a unique list of Sensors
         """
         all_objects = []
         for s in nested_list:
@@ -249,7 +260,6 @@ def flatten(cls, nested_list) -> list[int]:
                     all_objects.extend(s["sensors"])
                 elif "sensor" in s:
                     all_objects.append(s["sensor"])
-
         return list(dict.fromkeys(all_objects).keys())
 
 
@@ -427,3 +437,41 @@ def _deserialize(self, value: Any, attr, data, **kwargs) -> GenericAsset:
     def _serialize(self, value: GenericAsset, attr, obj, **kwargs) -> int:
         """Turn a GenericAsset into a generic asset id."""
         return value.id
+
+
+def extract_sensors_from_flex_config(plot: dict) -> list[Sensor]:
+    """
+    Extracts a consolidated list of sensors from an asset based on
+    flex-context or flex-model definitions provided in a plot dictionary.
+    """
+    all_sensors = []
+
+    asset = GenericAssetIdField().deserialize(plot.get("asset"))
+
+    fields_to_check = {
+        "flex-context": asset.flex_context,
+        "flex-model": asset.flex_model,
+    }
+
+    for plot_key, flex_config in fields_to_check.items():
+        if plot_key not in plot:
+            continue
+
+        field_keys = plot[plot_key]
+        data = flex_config or {}
+
+        if isinstance(field_keys, str):
+            field_keys = [field_keys]
+        elif not isinstance(field_keys, list):
+            continue
+
+        for field_key in field_keys:
+            field_value = data.get(field_key)
+
+            if isinstance(field_value, dict):
+                # Add a single sensor if it exists
+                sensor = field_value.get("sensor")
+                if sensor:
+                    all_sensors.append(sensor)
+
+    return all_sensors
diff --git a/flexmeasures/data/schemas/utils.py b/flexmeasures/data/schemas/utils.py
index a628add7a8..149d891f39 100644
--- a/flexmeasures/data/schemas/utils.py
+++ b/flexmeasures/data/schemas/utils.py
@@ -5,7 +5,6 @@
 from pint import DefinitionSyntaxError, DimensionalityError, UndefinedUnitError
 
 from flexmeasures.utils.unit_utils import to_preferred, ur
-from flexmeasures.data.models.time_series import Sensor
 
 
 class MarshmallowClickMixin(click.ParamType):
@@ -86,39 +85,6 @@ def convert_to_quantity(value: str, to_unit: str) -> ur.Quantity:
         )
 
 
-def extract_sensors_from_flex_config(plot: dict) -> list[Sensor]:
-    """
-    Extracts a consolidated list of sensors from an asset based on
-    flex-context or flex-model definitions provided in a plot dictionary.
-    """
-    all_sensors = []
-
-    from flexmeasures.data.schemas.generic_assets import (
-        GenericAssetIdField,
-    )  # Import here to avoid circular imports
-
-    asset = GenericAssetIdField().deserialize(plot.get("asset"))
-
-    fields_to_check = {
-        "flex-context": asset.flex_context,
-        "flex-model": asset.flex_model,
-    }
-
-    for plot_key, flex_config in fields_to_check.items():
-        if plot_key in plot:
-            field_key = plot[plot_key]
-            data = flex_config or {}
-            field_value = data.get(field_key)
-
-            if isinstance(field_value, dict):
-                # Add a single sensor if it exists
-                sensor = field_value.get("sensor")
-                if sensor:
-                    all_sensors.append(sensor)
-
-    return all_sensors
-
-
 def snake_to_kebab(key: str) -> str:
     """Convert snake_case to kebab-case."""
     return key.replace("_", "-")
diff --git a/flexmeasures/data/tests/test_SensorsToShowSchema.py b/flexmeasures/data/tests/test_SensorsToShowSchema.py
index 95ca1ecbb6..2780baf5b2 100644
--- a/flexmeasures/data/tests/test_SensorsToShowSchema.py
+++ b/flexmeasures/data/tests/test_SensorsToShowSchema.py
@@ -1,6 +1,7 @@
 import pytest
 from marshmallow import ValidationError
 
+from flexmeasures import Sensor
 from flexmeasures.data.schemas.generic_assets import SensorsToShowSchema
 
 
@@ -47,6 +48,38 @@ def test_dict_with_asset_and_no_title_plot(setup_test_data):
     assert schema.deserialize(input_value) == expected_output
 
 
+def _get_sensor_by_name(sensors: list[Sensor], name: str) -> Sensor:
+    for sensor in sensors:
+        if sensor.name == name:
+            return sensor
+    raise ValueError(f"Sensor {name} not found")
+
+
+def test_flatten_with_multiple_flex_config_fields(setup_test_data):
+    asset = setup_test_data["wind-asset-1"]
+    schema = SensorsToShowSchema()
+    input_value = [
+        {
+            "plots": [
+                {
+                    "asset": asset.id,
+                    "flex-model": ["consumption-capacity", "production-capacity"],
+                    "flex-context": "site-consumption-capacity",
+                }
+            ]
+        }
+    ]
+    expected_output = [
+        _get_sensor_by_name(asset.sensors, name).id
+        for name in (
+            "site-consumption-capacity",
+            "consumption-capacity",
+            "production-capacity",
+        )
+    ]
+    assert schema.flatten(input_value) == expected_output
+
+
 def test_invalid_sensor_string_input():
     schema = SensorsToShowSchema()
     with pytest.raises(
diff --git a/flexmeasures/utils/coding_utils.py b/flexmeasures/utils/coding_utils.py
index 0c1607efc6..0a951bc053 100644
--- a/flexmeasures/utils/coding_utils.py
+++ b/flexmeasures/utils/coding_utils.py
@@ -71,54 +71,6 @@ def sort_dict(unsorted_dict: dict) -> dict:
     return sorted_dict
 
 
-# This function is used for sensors_to_show in follow-up PR it will be moved and renamed to flatten_sensors_to_show
-def flatten_unique(nested_list_of_objects: list) -> list:
-    """
-    Get unique sensor IDs from a list of `sensors_to_show`.
-
-    Handles:
-    - Lists of sensor IDs
-    - Dictionaries with a `sensors` key
-    - Nested lists (one level)
-    - Dictionaries with `plots` key containing lists of sensors or asset's flex-config reference
-
-    Example:
-        Input:
-        [1, [2, 20, 6], 10, [6, 2], {"title":None,"sensors": [10, 15]}, 15, {"plots": [{"sensor": 1}, {"sensors": [20, 6]}]}]
-
-        Output:
-        [1, 2, 20, 6, 10, 15]
-    """
-    all_objects = []
-    for s in nested_list_of_objects:
-        if isinstance(s, list):
-            all_objects.extend(s)
-        elif isinstance(s, int):
-            all_objects.append(s)
-        elif isinstance(s, dict):
-            if "sensors" in s:
-                all_objects.extend(s["sensors"])
-            elif "sensor" in s:
-                all_objects.append(s["sensor"])
-            elif "plots" in s:
-                from flexmeasures.data.schemas.utils import (
-                    extract_sensors_from_flex_config,
-                )
-
-                for entry in s["plots"]:
-                    if "sensors" in entry:
-                        all_objects.extend(entry["sensors"])
-                    if "sensor" in entry:
-                        all_objects.append(entry["sensor"])
-                    if "asset" in entry:
-                        sensors = extract_sensors_from_flex_config(entry)
-                        all_objects.extend(sensors)
-        else:
-            all_objects.append(s)
-
-    return list(dict.fromkeys(all_objects).keys())
-
-
 def timeit(func):
     """Decorator for printing the time it took to execute the decorated function."""