If you own two cars and are able to make payments on only one and are letting one get repossessed can the finance company for the repossessed car do anything toward the remaining car?

Possibly yes. They can resale your repossessed car dirt cheap and sue you for the difference in what you owed and what they got for it. Then they can sue you to collect that difference. If they win the suit they can have the sheriff pick up anything you own to sell at public auction to help pay that money they supposedly "lost". It's possible but not real likely. It depends on the mob that runs the finance Company