I think I put too much corn syrup in my modeling chocolate. It's not firming up.
I wrapped it and set in on the counter overnight as the recipe directed. Right now I have it in the fridge hoping it will firm up. If it doesn't can I reheat it and add more melted chocolate to it or can I add powedered sugar to it to firm it? any suggestions would be greatly appreciated!

Yes, you can melt chocolate and add more to it.