Converting a bed from TS3 to TS4

Hello

I use to convert TS3 items to TS4 for my game, but i can't manage with beds. I have 5 groups when I import the TS3 mesh (waterfront obj ) in Blender, and only 3 ones with the TS4 mesh. So I tried many combinations, and I also tried to join the groups for the mattress (in order to reduce to 3 groups instead of 5). BUt nothing works.

I've seen CC beds converted from TS3, so it seems possible. I'm likely doing something wrong  with the mesh. Could someone help?

Thanks