I think you did a super job of adding on without it looking "added on." I've been thinking about adding on to a couch size quilt for my son. I see that he has it thrown over his queensize bed. There are a lot of pieces left from that quilt so adding on would work. I was thinking that I'd remove the binding and add borders by the QAYG method....applying the batting and backing together as with the 6-hour quilt. But using your idea would save that step of removing the binding (I cringe at the thought of unsewing!). Thanks for sharing!