yea the merge xml does not have the skeletonlink. If compared to ninja, ninja has 2 submeshes, but my merge xml has 1 submesh only. I also tried to copy and paste in all the xml to merge it to one, but it has "<boneassignments>" in each mesh xml and I have no idea what key is used to group them tgt (they are not in ninja xml though). I think it's still incorrect when exporting.
Or worst case, is it possible if we merge them using raft source code manually instead?