In the case of smart props, the object receives an underscore just the same (unless one is already added in the pp2 name directive), but the internal name used has a :# added where # is the number of the heirarchical level down the object is, from what I can tell. Actally, it's not the proper heirarchical level. For instance, on the thing I'm working on, I made a smart prop wand which becomes ElfMageWand_1:3 though it shows up as ElfMageWand_1 in the list and by name. I hacked an lt2 file into it to provide a smart-light spotlight that loads with the prop automatically parented to it. (it worked). On the MAT file thing, why not just make multiple prop files? If the props point at geometry (that is, an external OBJ rather than internal geometry), the filsize difference is negligible.