Mother in law have 1 plot sor por gor and 1 plot sor kor 1 and its current in my wifes grandfathers name. I understand its not possible to transfer the land since its plots given by the government. 1:Is it possible to change the name on the deed to my wifes mum or even my wife(from the grandfathers name) ? 2: If not, can they(at the land office) make a note or something in the computer that my wife is the grandchild, for make things easier in the future?

Personally, I would only build/invest on a red stamped Chanote in wife's name.

 

Only 1 person to worry about.  Invest what you can afford to lose.  Think of the 'what if' consequences if wife suddenly (Buddha forbid) passes before you.