To multi-quote, I use a right mouse click to open the quote in a new reply window, and then I cut and paste that into my reply. I then edit down what's within the quoted area, to reference only the portion to which I'm replying. Hope that makes sense. The idea is to give enough information that folks understand my reply, but to limit the overall size of my reply. Didn't appear to succeed in the super long reply above!
-- but, had a lot of catching up to do!
Cool your records turned out to be worth something! Vinyl has been coming back for a while. Sounds like you had good timing on reducing your collection!