Would you consider doing another story, similar to sweet dreams?
with mark x oc. FemOc being 21 and a genius, has inheritance from her grandparents, having the oc finding out shes pregnant with marks baby the same as Eddie during the start of her intern year, but slightly different, the siblings eddie has and them being her mothers favourite still the same however have the ocs mother end up having more (maybe 2 or 3) children but she palmed them off on fem oc to take care of because they weren't her husband's children, maybe ages 5 - 2 years old.
Either mark and oc can see eachother again just as she goes into labor or oc and mark could have a relationship without everyone (derek, addison ect) knowing. Have a male oc take marks place with the addison cheating, but instead of male oc not applying for a job at seattle Grace like in sweet dreams, this male oc does apply and takes marks place in the sleeping with addison (obviously), callie, lexie, teddy and also being the dad to sloan Riley, Sofia and dying, eventually becoming friends with derek again like mark did in the show.
Female oc meets her biological father who is a doctor like henry, like eddie does and also her sibling(s) from him but one brother is already married like Daniel (could already work at seattle grace) in sweet dreams and the other one gay like Ben. Female oc has a gay bestfriend, whos also close with his family. Keep the ABBA thing as you could use amanda seyfried as fem oc and have fem oc and the best friends cousins meet up and sing abba at a karaoke night for old times sake, with mark and her new friends and family from seattle going to the bar with them. Or they convince joe to have a karaoke night at his bar.
