The children of your uncle are your first cousins. The children of your first cousins are you first cousins once removed. Thus the grandchildren of your uncle are first cousins once removed.
The related link I will make below explains how all this works.
Your sister-in-law is either the wife of your brother or the sister of your spouse.
In either case, her children are your nieces and nephews and her grandchildren are your great nieces and great nephews. You are great aunt or great uncle to her grandchildren.
However, if her grandchildren are descended from children she had before she became your sister-in-law (i.e. from a previous marriage), neither her children nor her grandchildren are related to you.
Yes, unless you, your grandpa or your parent who is the child of your grandpa, were adopted.
Your grandparent's first cousins are your first cousins, twice removed.
The grandchildren of your grandparent's first cousins are your third cousins.
Your grandfather's sister is your great aunt. Her son's daughter is her granddaughter.
The grandchildren of you great aunts and great uncles are your second cousins.
Your grandchildren and your nephew are related t each other as first cousins, once removed.
Your grandfathers' sisters' grandchildren are your second cousins.
Your grandchildren and your great niece are second cousins to each other.
Your niece is the first cousin of your children and the first cousin, once removed, of your grandchildren.
Yes he has only 5 Actual grandchildren the other 5 are not related. They are his second wifes grandchildren from his widow's first marriage
There is no word in the English language for a relationship between grandmothers of related grandchildren
Your children are the first cousins of your brother's children, and the first cousins once removed of your brother's grandchildren.
Your children are the parents of some of your grandchildren. They are also the aunts or uncles of those of your grandchildren who are not their children. Even you have a child who is younger than one of your grandchildren, that child is still the aunt or uncle of all those grandchildren.
If I knew the answer, I wouldn't have asked it!
Adam was the firs person on the planet...
Your grandmother's sister's grandchildren are your second cousins.