Yeah, I'd remembered that too, Scorpius talked to Rose a lot about quidditch (I think she chose Beater position). So we can handwave that there had been quidditch and flying practice if you want.
Y/Y, totally agree to Rose and Damien being acquainted as they have Kirk as a friend. She'd probably have seen him around as a neighbor when in Greaves.. also might be either awkward or amusing that Damien sorta resembles Christian. I'd think in looks only, Damien has differences like business outfits, his walk and manner, the fast car, etc.
Also, Skye and Ward might have seen Damien earlier at the candlelight park thing since he had also went to that too. Tossed Damien into the Rose thread. Might do Scorpius in a bit too since it's multiple options, as well as having them both start their own OTA sub-threads in here, just in case anyone else might want logging with them. :)