You can't just "convert" them. You still have to sell them to someone, can't force that. Even if you could that would pull the price down extremely. Easiest th

You can't just "convert" them. You still have to sell them to someone, can't force that. Even if you could that would pull the price down extremely. Easiest thing is to just give the user access to the new chain and it's "parallel"-coins. Then he can decide when and how to sell them.