@jcparent , I think your question about openings is a fair one given what you are putting into the process. Personally, I would try for 6th and if that doesn’t work, apply again at 9th. Showing interest helps.
It’s also possible that a completely different option would suit your girls better at 9th - even with acceptance at one of those schools. Kids leave for all kinds of reasons, including not liking the social vibe.