My husband has two sisters who are both married.
They are all lovely and we get along, one brother-in-law is maybe a little self absorbed but good company and generous in his hospitality when we are in his house.
These brothers-in-law have no interest in attending family functions.
Since FiL died MiL relies on her daughters. They take her away and go on day trips or even just a drive to the garden centre.
They went to New York for her 70th and my DH went as well. I was jealous but I have lots of trips away.
However, I see this family is my family, their children as my nieces and nephews; the brothers-in-law see this family as their wives’ family and they don’t see see our children as their nieces.
What is happening increasingly is DH goes out/away with his sisters and his mother (sometimes with the kids) without me because spouses aren’t included because these brothers-in-law aren’t interested. They get excited that they get the house to themselves for a few hours/ a couple of days.