Hi all.
Well, to keep it simple.........
We got on every single segment of our journey, there and back, with no more than a casual look at my sisters marriage certificate. In fact TSA at Orlando did NOT notice that passport and boarding pass was in two different names.
So no need, as some speculated, to have to purchase a new ticket.
Thanks for help and advice, and thank you to ticket/ground staff of continental/united at EDI.