Sexlab and NPC with differents bodies

[spudmonster]

I have a small strange problem with sexlab.

I play on a heavy moded skyrim with sexlab, all work finely.

I have a homemade mod with about 100 females NPC modified with different body.

When I start a sexlab animation with those NPC, sometime they use their custom body, and sometime the basic body.

And I can't find why (and I know nothing about FNIS and animation)

 

Some solution ? or advice ? And it's always good too learn about moding.