DP's parents split when he was a baby, his mum took him about 100 miles away from his dad, if relevant this was in the 1980's.
A few years later DP's mum died suddenly, DP's father came and got him and raised him, but it was never a close relationship, having said that for some reason, all contact with DP's mum side of the family stopped.
DP's dad died 8 years ago and all those questions my partner wanted to ask him about that time never got answered.
DP asked me to do a bit of research and see if I could find his mum's mum (I don't work, he does) I found the most recent address I could.
DP wrote her a letter, that was 6 weeks ago, logically we are talking about a good 30 years and she could of moved, I am fairly sure she is still going, but I am not expert, we haven't got the letter back and he is now faced with more questions than answers, I am not sure what else he can do.
Should mention as well, he is not close to his dad's side of the family and he has asked them, but (IMO) they seem to avoid the question, but I am not sure if it because they don't know why DPs dad cut contact or they do and don't want to say