JCM interaction two or more limbs

Diomede

Using a skirt as a learning exercise.  I created JCMs to smooth the front of the skirt when each thigh was bent forward separately.  I followed a Josh Darling tutorial to add the JCMs to the skirt and link to the correct bend.  So far so good.  However, if both thighs bend forward at the same time, such as a sitting position, the middle interacts in an undesirable way.  I modeled a sitting morph but don't know how to add it appropriately. 

- what are my options (could include not using a JCM and doing something else)?

- which option would you recommend?

- can you point me to a tutorial for the recommended option?

 

each JCM seems to work OK when each thigh is bent seprately

undesired interaction when both thighs bent at same time (yes, I have modeled a sitting morph but don't know how to link to this situation)