I hope I described the workflow above clearly.  I would suggest trying it on some simple meshes before doing complicated stuff. If you do a mesh with one group you can ignore all that messy converting groups to materials and back.  You can define your constrained group inside the clothroom but I find that very messy.

One thing I didn't mention is that the polygons which you use as the constrained group really need to be in their correct position, with regard to Antonia ( or whatever you are shrinking onto)  since they will stick in place. I'ts one of those things that is easier to do than to describe, so like I said, try a few simple shrink fits

If you do try it, and have  any problems, please let me know and I will try to answer. I'm sure there are other ways to achieve the same end result.

Cheers

Ian