Asset distribution to heirs

My father in law is 78 years old, has self acquired 3 residential plots in my mother in law(home maker without any income)'s name. She died in 2011. He has two children, one girl and one boy. The girl is my wife. The boy is also married and having a minor son. My brother-in-law is spendthrift and not a trustworthy person. Please suggest the best way to distribute the assets to his daughter and the minor grandson, totally ignoring the son.