extended family

well, this is the story. honestly, they fight over small things and later on my brother in law moved out from their house alone and left his wife and son without anything. as in literally empty handed. he left all his clothes, important papers and everything. only the clothes he wore that day and his one way fare to our house. there fight involves money matters, third party and also some physical like allegedly my brother-in-law hit his wife which we later on found out that it's the other way around. He didn't left their house instead he was sent out of the house, and the worst thing was that their neighbor saw that it's the wife who hit the husband. They used to live in the house of his wife's aunt who really got mad with my brother-in law due to false accusations of his wife. Then eventually, when the relatives found out what really happened they send away their niece who in return followed his husband who then stayed w/us. We advised them on how to handle their problems based on our own experiences as husband and wife because we don't want them to separate for the sake of their child and so they reconciled and patch things up. What's so irritating was that they can't even support their child's needs like his milk when we all know that they have the means to do it. What we wanted them to do is at least prioritize their child just like what we do with ours so as not to harrass other people because it is not our responsibility anymore. I've talked to my husband about it and his advice to me is to talk directly to the wife because we are both mother and maybe she will listen to me.