詳しい回答者がいないようなんで、ちょっと助け舟

3BAは、 CBPCollisionConfig_Female.txt の中で設定するのがよかった筈

[ExtraOptions] で Bellyの名称が付いてる所で調整できるが
詳しい内容はわすれてまった。#以降の英文訳して試行錯誤してちょ

ちな今の俺の設定
腹ボコを控えめにする感じにざっくり弄った筈。参考値として晒しとくわ

##############################################################################
# Extra Options
##############################################################################
[ExtraOptions]

BellyBulge=1.0 #This is the multiplier for the new special belly bulge for vagina penetration. Higher values would cause a bigger lump on the belly. 0 would disable this special setting.

BellyBulgeMax=5.0 #This is the horizontal max position of the belly bulge

BellyBulgePosLowest=2.0 #This is the vertical position of the belly bulge

BellyBulgeReturnTime=1.0 #This is the duration takes in seconds for belly bulge to return to its original position.

VaginaOpeningMultiplier=3 #This is the multiplier for vagina opening.

VaginaOpeningLimit=8.0 #This is the limit for vagina opening.

AnusOpeningMultiplier=3 #This is the multiplier for anus opening.

AnusOpeningLimit=8.0 #This is the limit for anus opening.