You can just use cheats to reset the routes, so you don't need extra saves.
I gotta say though, I prefer slave routes for these characters. Sylvia seems annoying and kind of spoiled. She's glued to the TV all the time. Nia is... I guess 'radical activist' is the correct term, but mostly she seems like a shortsighted thug.
Her actions are saving people, but her waving her bat in my face rubbed me the wrong way.
Taking them both down a peg is very satisfying. I'd prefer if it got a fuller route, equal to the lover route.