Oh, I just saw your post about wanting them to make an effort for dh. I understand, but I don't think their rift is about you and him. You say you don't know what caused it and haven't asked and that's wise, imo. But it might be deeper than you can imagine and not something they can overlook for a day or even an afternoon. Even if they tried, there's bound to be tension, the "elephant in the room" thing. Would you and dh really want that?
If we were talking about a huge celebration like a retirement party or a wedding vow renewal, then I might think they should try to put their differences aside for the day/evening and just stay as far away from each other as possible. People do it for weddings and such all the time. But for every holiday and birthday, etc. No. If you and dh were planning a huge shindig for his birthday, then, again, yes, I could see expecting that. But otherwise, I think you both need to forget this idea. It's not likely to happen.
4 Years On…..Health-wise, Has Anything Changed?
To think that London, or anywhere else for that matter, does not belong to any one demographic