not to be complicated , but if you have an uncle-->
he has a nephew--> as you can see that's not complicated .
And if you ask what is a uncles NEPHEW related to an uncles grandfather.
in what way ....i would say the nephew is is the great gandfathers great grandson.
Your uncle is your child's great uncle and your grandchild's great great uncle. Your grandson is your uncles great great nephew.
The children of your grand nephew (or great nephew) are your great great nephews and great great nieces (depending on whether they are girls or boys).
Your nephew's child is your great nephew or great niece depending upon sex.Your nephew's grandchild is your great great nephew or great great niece, depending on sex.
The grandchildren would be the parents, aunts and uncles, and first cousins once removed, of the great grandchildren.
Your child and your nephew are first cousins, so your grandchild and your nephew are first cousins once removed.
A great great nephew is the great grandchild of your sister or your brother.
If you have a niece or nephew, it is their daughter.
Your sister's great grandchild is your great great niece or great great nephew.
Great niece or nephew.
Your brother's great grandchild is your great great nephew (if a boy) or great great niece (if a girl). You are their great great aunt.
You brother-in-law is uncle to your children, so his great nephew could be the son of your child, also called your grandchild, or the grandson of one of your siblings who are not married to your brother-in-law, and thus your great nephew as well. But your brother-in-law can also have great nephews who are not related to you at all.
I believe they would be great aunts or great uncles.