In theory I think it could be fine in a different situation. However with them being third years, plotting just because of a similar name might have already been done in their past? I'm not saying it couldn't still happen, just that it seems unlikely. I've read through the conversations you and Billie had on Sebastian's classified and it doesn't sound like she actually said it would be okay for both of you to have the same/similar first name -- she proposed you use the middle name instead, and I honestly think that's safer, both to avoid confusion and because Billie's character is now already Sorted. Bringing in another Sebastian in the same year after one is already established, even if you put that WIP over your other WIPs, could imply that there were mix-ups that weren't played out before (they knew exactly which Sebastian they were talking to before, and now there's a possibility of two that were in school all along). Georgia had a similar situation where she wanted to name her professor Theodore and ended up making it Emmett's middle name instead. So personally I'd have to say no to the same/similar first names, sorry hun! ^_^