Many thanks to @vagonumero13 for giving us this new powerful tool. I just tried his idea of adding meshes --- making my self a little more trouble by trying the softbody meshes. The purpose was to add suspender strips to MOM_033 mini thong mod:
(Mod is attached)
There is no point to open a new topic just for a little mod, so I will also show how I add the softbody meshes with the g1m_xml tool. I assumed you already know how to import/export and handle VB/IB with Blender.