When I try to combine meshes and then add them into my mod I get ctd's from in game and in the CK. Once it's set in the CK without combined meshes, I then edit the meshes and the CK doesn't seem to register the changes so the CK doesn't crash. In game, it doesn't ctd straight away, it seems like it hasn't registered the combined mesh until a few minutes of game play.

I usually just open the two meshes, copy branch and then paste it into one under the main branch. This way seems to be causing problems, anyone know how to properly combine meshes?

Thanks.