Instead of requiring an entire rib to be C1, specified 1st derivative, etc. make that for each rib segment. This would require the user to know where all of the joints are on the rib during construction and ensure that all curves associated with rib are split in same location. This might be an advanced construction technique that can be facilitated with a GUI configurator where the user clicks on segments and sets conditions, splits, etc.
Also, need to have the ability to specify conditions at point on rib. For instance, at t=1 want C1 and everywhere else want C0.
This can get quite complicated quite quickly.