EBORR:
Maybe I can help...
If you, say, want a sci-fi wall with a ww2 floor and ceiling...
You cannot select the whole segment. You will have to select the individual wall and the individual floor.
When you paint with walls and you have a whole segment highlighted, FPSC will assume that you are using that segment, so it will overwrite the floor with the corresponding wall.
Ever noticed how when you select a whole segment and you look at your library on the left you see the whole segment AND the individual parts?
That's what I mean.
Try it out. Avoid the whole segment and select the individual part of the segment if you want it to work.
I may be wrong, so a more experienced person on here can hopefully chime in and support or reject what I am saying.
But it worked for me.
Hope this helps you.
GAME ON!!!
--King Cobra