you might want to explore a instance variable.. imagine "Is_Solid" and you put in the conditions that require an object to have that be 1 not 0.. or if you want to use a bool.. though i've found just using numbers works fine.
there is an "initial state" which seem like a good thing that you might be able to toggle.. or maybe you could have a duplicate object one that has solid and one that doesn't.. and when you switch, you destroy one and spawn the other..
That's what comes to mind for me. There are other ways probably that I don't know about. I'm not an expert C2 user.