If you want to use V4 based dynamic clothing on La Femme, you can use the prefitter with LaFemme injection to make the initial fit. Use the Prefitter cr2 as collision object and in a sim morph to the La Femme shape.

Alternative idea, not tested yet: Load the Prefitter cr2 and La Femme into the scene, zero La Femme. in the Prefitter set LaFemme morph to 1.0 so Prefitter lines up with LaFemme and copy the V4 to LaFemme morph from the Prefitter into La Femme. Delete the Prefitter and in La Femme set that morph to -1.0 at the start of the simulation (the garment should then more or less fit La Femme. and to 0.0 somewhere in the run of the sim. LF will then gradially morph from roughly V4 shape to her own shape. Of course if you save the LF to V4 morph for La Femme you need to do the copy from the Prefitter only once.

Keep in mind that for dynamic clothing size is important. If you try to sim an XXL size model into an M size garment, the result will be an M size garment spanning around an XXL person. The garment does not grade up. Likewise, pants that would stay put on an L size figure end up around the ankles of an M size figure, unless you make the belt constrained.