(Custom MHuman Clothing) Anyone know why this happens?

I was trying to convert some Reallusion Character creator clothing to MetaHuman ( never done it before ), and the biggest challenge is that the RL MH compatible characters don’t neccessarily match the proportions of whatever the default bodyShapes in UE MH, so I was expecting the proportions for the clothing to be off, however, the arms and the legs actually seemed to be not angled properly with the MetaHuman when I supply any of the bodyShapes as a Source Body Part to the Chaos Clothing on the MH Wardrobe.

However, if I set it to null, suddenly the angling of the legs and arms actually do match the metahuman ( height proportion is still off, but thats probably because of the differences between the Reallusion base and whatever Metahuman is expecting ).

Anyone know why this is? Also does anyone know if CharacterCreator has a body that just matches one of the UE Metahuman bodies, or if there is some way to tweak this within UE?