I commented in another post this morning about the same issue. The closest person..the spouse..seems to be the one blocked. After 60 years together, I still don't count as part of the past my husband remembers. His sister is the most clear to him. I don't think it has anything to do with your MIL blocking her husband due to emotional issues, although in this case, it sounds like a blessing. My mother in law remembered her first husband who died tragically; but she didn't remember her second husband who was a dud. We all enjoyed that blank in her memory, so sometimes it is a plus.