Just noticed, when typing in another thread, that I referred to the daughter of my ex-marriage as 'my daughter' and not 'our daughter' . I think this must be because, once divorced, I thought that there was not an 'our' involved since we are not a couple, 'us', but a 'you and me'. Mind, her mother still calls her daughter 'Your daughter' when the girl has annoyed her so much that her mother feels compelled to speak to me about it, for my intervention !
If there is any relevance to saying 'our daughters' then it would be because either the mother is in the conversation, or the people in conversation are familiar with the mother. If no to either then I always say 'my daughters'.
I don't think it makes that much difference being separated or divorced?
my sister always splutters when I refer to "my great great grandmother" or similar: "She's OURS!" In which case, I reply, perhaps you'd like to reclaim her by doing some of the family history research yourself.
Even those of us who are not divorced or separated suffer from a similar problem Fred, I am quite often (perhaps rightly) criticised for referring to my child, or my money, or my idea when of course I mean “our”, my argument that it is just a figure of speech is not accepted.