I don’t think Across the Stars needs to be used. It’s just Anakin and Padmé’s love theme, not a general one. However I think you could place it in the scene where Ben resurrects Rey and it would work well. Mostly because Anakin and Padmé’s relationship was torn apart by Anakin trying to save her. Now Ben literally brings someone back from the dead, so it might be a nice way to tie the prequels together as well. I don’t think that’s necessary though.
That’s exactly why I’m split on using it.