Hi to all!
Experiment 1:
Install UNP Skinny.
Install femalebody_1.nif from UNP Main (i use B2).
Result:
Now you have a working weight slider from Skinny body (at 0%) to Main body (at 100%). These meshes a fully compatible.
Experiment 2:
Install UNP Skinny.
Install femalebody_1.nif from UNP Main femalebody_0.nif file.
Copy femalefeet_0.nif to femalefeet_1.nif and femalehands_0.nif to femalehands_1.nif.
Result:
Now you have a working weight slider from Skinny body (at 0%) to Ma