Loading new fbx into SPP?

Hi,

i am trying to load a different fbx into an existing painter file using edit-project configuration... however when the new fbx loads all my layers are gone. it is a set of 3 uv tiles. in the new fbx i also created 3 uv tiles.

I need the layers to stay so i can reassign them to the new fbx. 

What am i doing wrong? 

thanks,

Bart