I can remember when I was growing up, my aunt had an entire house of antiques and breakables. She always said she refused to put them away and said she never had a single thing broken in all her years of having kids visit. She had expectations and we all knew it. That being said, kids are raised differently these days. I never kept any breakables in my house, even Christmas ornaments, because between kids, cats and dogs nothing would have survived. My children still know how to behave in other peoples houses by 5 and 7.
As for the issues at hand, have you considered planning out a menu and asking the kids to cook with you? It could be a family affair.
Kids learn to love more types of food when they have a hand in making it. You could even reach out to mom first and say, I want the kids to cook with me, can we speak about a menu they would enjoy? Let them makes some choices and you make some choices and everyone agrees to try one bite.
This will keep them busy and out of your sitting room and you all may learn to enjoy each other's company more.
If all else fails, find somewhere outside to sit and visit.