My father in-law has been dead for 10 years, just recently we found out he has a 24 yr old son out of marriage. What are the child's rights in the state of Ga. To land my mother in-law owns? The land did belong to my deceased father in-law.)

When you say it belonged to your father in law what exactly do you mean? Another thing is that if its not being contested at this time is there a reason your asking about it?

Ref:

Georgia Inheritance-Inheritance tax and law | Global Property Guide


Georgia Rules of Inheritance