Hi Claire- I had to weigh in on this one because I am going through something similar.
Since he wants D5 to feel like both places are home - what is his suggested phrasing?
I probably caused a problem in my own situation because my daughters had started simply referring to the locations as "Mommy's house" and "Daddy's house" and that bugged me because I wanted them to feel like they have a home (or homes). So I started emphasizing the term home when we were on the way back from the grocery store and places like that. They must have repeated it to XH because they came back from a visit saying "Daddy says his place is home too". To which I said "That's right - it is your home too". On reflection I think I was making a mountain out of a molehill on that one. Kids don't attribute the same emotional weight to words as we do. And when I was uncomfortable with the use of "house" versus "home" - it was more about my fears for them rather than their not feeling they have a home.
So - I would ask him for his proposed solution, but also point out it probably isn't realistic that you are going to be able to police your phrasing 24/7.
