Custom outfit studio bodies don't gradually change from 0-100 and neck gap

[LLuser13]

From 0-99 I get body_0  and at 100 I get body_1 and no neck gap. The closer i get to weight 0 the higher up npc' necks pull away from the shoulder creating a neck gap. the thing is all i do to the bodies before and after the problem is make the butt ridiculously big. There's got to be a way i'm just unaware of to fix this problem but I can't find it nor can I spend too much time reading books about meshing

 

Also Idc about body_0. i simply made it because to see if it would fix the problem which it did when it was straight out of bodyslide but once I used body_1 as a reference and tinkered with it the prblem came back

femalebody_0.nif

femalebody_1.nif