The molly has been not too bad the last few days. I've been adding some freeze dried daphnia to their diet which keeps the molly occupied at the top of the tank while the corys get their sinking food. The problem seems to be that the molly can't stand the fact that the corys are eating while it is not.
I'm also still thinking about setting up the 20g as a brackish tank though. The molly would probably be happier in it. I'll take a look and see if there is anything compatible in that area.