Sorry... Xelloss, I didn't mean to imply that I 
thought you had a problem with putting 
backgrounds that don't match with a cel. ^^;; 

What I meant is that I personally don't see a 
problem with it, and that I have purchased 
backgrounds to add to my cels.  However, if 
someone does this, it should be clearly noted 
should they ever go to sell the cel. ^^;;

It's too late.. wasn't thinking before I 
posted. :)