I was interested because I had purchased Bella1.1 in and wanted to add a Bella mannequin to the MDBridge for Poser. These mannequins are essentially skinsuits that come without all the humbug that makes the original figure less suitable as an avatar in MD.

The below is a plain fitting room result; just figure plus suit in and figure out. The mesh ensity of the suit is about 8 times as high as Bella's.

There are bumps in the weigth maps. As far as I can see this is the fitting room having interpolation problems on the coarse mesh. It is not a Bella problem.
My conclusion is that the geometry of Bella is on the low side to be used as a target in the fitting room. She would need a dev figure.

(Bella Mesh shown 1x subdivided)