Can someone help me understand the upgrade? I have heard that some airlines now allow you to go from F/O on a regional to F/O on a mainline w/o being a CAP at that same regional. Is this true?

Also, if you decide to go to an airline with a flow program such as PSA, do they make you sign on a contract saying you will stay on with them until you flow through? I guess I'm wondering why wouldn't someone just go for an airline with a flow program, and continue to apply with other legacy carriers at the same time to increase their chances of getting hired?

Sorry if these questions have already been asked...