Custom blockstate file (for multi-textured block)? [Never mind]

Basically, I'm trying to make a new mushroom block. I have the blockstate file that determines when it uses the mushroom block texture and when it uses the mushroom block inside texture (like Vanilla mushroom blocks). Is there any way I could put this into MCreator without it rewriting the blockstate file?

Never mind, actually, I don't have a way to define the blockstates in the first place.