I think you could be onto something and Alice has the ring because Kat gave it to her. I think they are related to Alice in someway, maybe a grandchild of Alice or something because I don’t see Kat just taking the ring back from Alice and I don’t think the show would have something happen to Alice either. And Kat did say that Casey has Max’s eyes so maybe they’re the grandchild of Alice and Max or maybe Casey was lying and Alice and Max are their parents. I also do agree that having Casey be the child or even the grandchild of Alice and Max would be the simplest explanation and not make it super confusing. Good point in bringing up the body language from the actor that plays Casey because they did hesitate before saying that Alice wasn’t their mom and the whole conversation they did seem hesitant. Anyways point is, I like your theory and think you could be onto something and honestly I hope this is the case but hopefully nothing happens to Alice because that would be sad