Loved this one, really hope to see more. I posted a review with most of the praise, so heres a couple of suggestions:
For Eloise: Breeding kinks are very much a mental thing, so the dirty talk can be more than half of the fun. Having the mc engage more with the talk would be what someone like eloise would enjoy. I'd also love to see her voyeuristic side explored more.
For Serah: I love the inclusion of the collar and the discussion of consent in free use relationships, but it would be even better if it was actually present in game when you interact with her around the house, cause now it kinda seems like you're violating the 1 rule you've set. It'd also be nice if you could interrupt her musical sessions, like during that one scene.
Besides that I think you're totally on the right track, so I trust in the development to expand on everything great here.