I like the rewrite with them being all sisters rather than one being the mom. IDK it feels like that's how that should be.
Also where's the torrent for this?
Actually I think I know why it feels right. The mom and dad are still together and the dad isn't off on some mysterious trip or dead to avoid the cheating tag. On top of that in the epilogue they support their relationship so they don't have to keep it a TOTAL secret.