The Force Contract option is for commissioners to use to advance the dynasty along without waiting for dynasty members to hop in and make their decisions.
For example, we are in a dynasty setup and wanted coach contracts but we didn't want everyone moving around. The idea was to stay at the same school and move up. During the coaching carousel, since I know all my coaches want to stay put for the time being I can select force pick when their name comes up and it gives me the option to force them to stay (there's also an option to force them into a new contract).
Naturally, there's no override option if they don't have a current contract. One of our guys got fired... so the only thing we could do was boot him and re-invite him.