Have you just installed 3BA/3BBB and are having issues with the promised vagina and belly physics?
Do you have a stickler for realism?
Do you have a fetish?
I probably can't help with the last two but:
YOU HAVE COME TO THE RIGHT PLACE
I have spent an afternoon trying to fix just that.
This guide or fix will go a roundabout way in helping you through this issue so that if you have more issues it may cover it. it will be divided into three sections