Is it against the rules to create a custom decor of an existing marking or a marking that looks similar to an existing one? The reason I'm asking is that I plan to get a 10x Rosette heir and eventually make him a 20x rosette, but I also want to keep an underfur marking for his appearance as well as maybe custom markings as I assume that a lion with only rosette markings probably won't look very good.

I figured it would be similar to making piebald/patches CDs for muties, but figured I should still ask in case.