Thanks. That seemed to work although it is not intuitive and it is, I think, a bit incomplete. This is because when I choose a folder on one machine it seems to automatically make a sync folder on the second: I have to first delete that 'automatic' folder then can link my chosen folder.
I could see it being a bit more user-friendly if, when I start the process on Computer A it allowed me to target then a chosen folder on Computer B. I could then go over to Computer B and "approve the request". This would be simple and not require any non-intuitive deleting and re-choosing folders.... Sorry if my terminology is a bit sloppy.
Thanks Richard