Whether it's right or wrong, it's not possible unless the birth parent's rights have been legally terminated.
Their own grand grand children...
Benign means not harmful. So for example, grandparents see their grandchildren as benign lovable children.
Their grown children and grandchildren won't visit.
No, the only way grandchildren can get benefits is if the grandparents have legal guardianship of them, as if they were their own children.
Your ancestry. Those you have descended from are your ancestors. My lineage includes my parents, grandparents, great-grandparents, etc., in my past, and my children, grandchildren, great-grandchildren, etc. in my future.
The grandparents can get access towards there grandchildren by the mother and father dies and they get them. Or the grandparents file for custody of the children
They teach their children and grandchildren the rules and laws of Shabbat.
Your ancestry. Those you have descended from are your ancestors. My lineage includes my parents, grandparents, great-grandparents, etc., in my past, and my children, grandchildren, great-grandchildren, etc. in my future.
Your ancestors are the people whose children lead eventually to you. They are your mother and father, grandmothers and grandfathers, great grandparents, great great grandparents, etc. Your cousins are the children, grandchildren, great grandchildren, etc, of the brothers and sisters of your ancestors.
Informing you that they have three grandchildren would be easier if there were names, dates, and ages, of the grandparents and grandchildren. This does not have enough information to state whether or not they do have three grandchildren.
Grandparents have no legal right to have custody over their grandchildren like parents do. Any relative have the same right to petition for custody if the parents are gone. If the parents are there they are the ones deciding where the child will live.Grandparents can have the right to petition for visitation though depending on which state they are in. That is something other relatives don't have. The laws differs on grandparents rights. The court usually don't go against parents wishes though.Another PerspectiveYou asked about grandchildren's rights to their grandparents. Unfortunately, the parents have the right to make decisions for their minor children. If the parents decide to keep their children from seeing their grandparents they may do so.
(in the US) Certain states have ruled that Grandparents DO have the right of access to their grandchildren, but this is not a universally held or universally enforceable decision. You will have to check with your individual state.