Sister in Law upsetting my mother
I need some help. I live far away from my family but am very close to them all. My brother and SIL had a baby 6 months ago and the family was thrilled. In the past few weeks though, my SIL has been excluding my mother on the milestones of their child. When asked about it my SIL got angry and said that my mom had posted a pic of her child when she told her not to and had lost the right to find out about her grandson on Facebook. (Their means of communication as my mom does not want to call in case the baby is sleeping or they are having a bad day, etc)
My brother has always had a chip on his shoulder about my parents. He feels he is getting the short end of the stick on everything. My parents recently sold their cabin as they are getting close to 70 and can not maintain the property the way it should be maintained. My brother was very upset, but could not afford to take over the property tax and bills. My parents would have willingly sold him the cabin at a fair price if they thought he could upkeep the place. My brother felt he should have just been given the cabin without any money being exchanged. My SIL even threatened to have an injunction put in so they could not sell the cabin thinking that it is my brother's birthrite and they had no right to sell it.
There are several other things that have added up to make my brother bitter and of course he shared these with my SIL. I told my SIL that her son is going to have the best grandparents in the world. They are loving and kind and their 4 other grandchildren think the world of them. My SIL disagreed with me. If my parents were putting my children in danger and doing horrible things I could totally relate and agree, but all the issues are from the past. My mom now feels that she has lost not only her grandson but her first born too. She is devasted. This woman does not cry and she has been close to breaking down more than once in the past few days.
My father and sister have asked me to talk to them as I have the best relationship with them. I fear if I do this I will also be out of the loop on my brother and his family. My mother and father are not perfect, but do they deserve to be shut out because my mom doesn't know how to use Facebook and ticked off my SIL?
Please advise as I have only a few days before my sister and dad start asking me to step in.