How beautiful, Nanna58!
Thistlerose, you do sound very down on sps, in general, even though you don't say "all." It seems to be from bitter experience though, so (((hugs)))
Zorro, it sounds as if there are a lot of concerns among your sc about money and whether they're being treated fairly. Idk if it's more about the money or the fairness issue. But I agree with those who say you and dh need to discuss wills and get them prepared. Very bad timing for sd to ask on Christmas. But to avoid that, imo, dh needs to tell his ac what his plans are regarding how inheritance will be doled out, etc. Maybe not specific amounts but things like, "I'm leaving everyone an equal amount" or "I'm leaving this one more than that one for this reason."
It's awful that his dds ambushed him that way. Imo, you 2 should have gotten up and left. I think you need to discuss what you'll do in the future if that happens.
Perhaps your sds fear they will be "cheated" in some way - by dh, by your ss, maybe even by you. Their fears may be unfounded, but, imo, dh needs to make this clear to them by spelling things out a little more. They're NOT entitled to this information, but it might calm things down.
I don't see why dh needs to pay the expenses of adult dds and ds. And, imo, he needs to say "no" more often. For example, sd needs to give her kids parties, sleepovers, etc. herself, NOT rely on her dad for this. But idk if there's much you can do about this.