Same seniority list for T fly and Mainline but there is a type freeze so should I go on the 73, I would have to be in for 5 years. No further bond though.
My guess is that you could move back and forth because it is all down to a bidding system but it obviously would take a while.
Also I can't see any problems as long as you are an FO but when it comes to Captain, I am not sure how it is going to work.
Still, all down to bidding so as long as you are on the seniority list, you should get a go at whatever you fancy.