Sorry, nope, sounds like it's a half-sofa for you for now. I do like the idea of asking for first right of refusal if she decides to trade up, though.
I think that would have worked best if it had been part of the offer to begin with. My friend moved and I took his couches. If he had said that he wants them back if I wanted to get rid of them as he was giving them to me then no problem. If he called me up a year later and said that he had been thinking about it and wanted them back if I wanted to get rid of them then I would find the whole conversation strange and be wondering if this was his roundabout way of asking for them back.
Yeah I would think so too. And I don't really like that when it happens.
Twice in the last couple of years I've been offered stuff conditionally and I always turn it down. If you're looking to get rid of stuff so it's no longer yours
and actually becomes mine
and I happen to need it - great. If you're offering me something that your grandfather made and want it back if I don't want it anymore then I feel as if it's on loan. And I hate borrowing things because what if I break it? Then I have to pay for it and I still don't own it.
I'm not saying there's anything wrong if someone offers something conditionally - it can work out great for a lot of people.
I did have one friend offer me a beautiful, twin-sized bed frame with drawers and shelved headboard. Her father had made it many years ago. She told me if I wanted to get rid of it, she wanted it back. I told her I appreciated the offer but no thanks. I'd be essentially borrowing it because I move a lot and if I moved out-of-state I'd feel compelled to give it back.
It was like she didn't even hear me. She brought it up later, huffing and puffing, that she gave it to someone else because I didn't let her know in a timely manner that I wasn't interested.

So I just said, 'that's nice, anyways about this beandip,' and we talked about other things.