Wonderful yiddish word - MACHATUNIM ( spoken pretty much phonetically), - which means the parents, etc. of your son and daughter in laws. No proper word in English to cover this 'relationship'.
So, I four currrent machatunim - one I have never met as my DiL's parents live in USA, and have never actually come here, although they have now been married for nearly twenty years. They go there to visit (when virus permits).
The others, I have all met, and know. Only one I would really get on with, but as she loves in North Yorkshire, not really the opportunity.
My daughter, who never married, and whose ex-partner - (father of her daughter) sadly died a few years back, does get on extremely well with his sister and family. Not so much with his Mum (who is DM reader - which says it all).
My parents took into their bosom my to-be MiL who was a widow. They paid all her costs for our wedding, and she would be round their flat every weekend for afternoon tea. She and her daughter were always included in our families Christmas arrangements, etc. When a few years later she re-married a wealthy man, she virtually cut my parents out of her life - and I could never quite forgive her for that.