A person's granddaughter's husband.
If you really need a relationship term, use granddaughter-in-law. Most people would merely say "my grandson's wife."
The grandson of your first cousin and your grandson are third cousins to eachother.
Louis XVIII. was the grandson of Louis XV
Your niece and one of your grandson's parents are first cousins. That makes your niece a first cousin once removed of your grandson.
No.
My daughter's husband is my son-in-law, so is my granddaughter's husband my grandson-in-law? Pat
Your grandson is your brother-in-law's great nephew, and your brother-in-law is your grandson's great uncle.
Your brother-in-law is your spouse's brother. His grandson s your spouce's great nephew. (Some people say grand nephew). That makes him your great nephew, too. Your brother-in-law could also be the husband of your sister. Then your brother-in-law's grandson is your sister's grandson and your great nephew.
If your daughter-in-law's grandson is a child from a marriage before she married your son, or after their marriage ended, her grandson is not related to you. If he is a child of the marriage between your son and your daughter-in-law, then he is your great grandson.
He is your grandson by marriage or grandson in-law.
Grandsons-in-law
There is no real blood relationship, as you do not share a common ancestor. You could refer to him as your grandson-in-law. It is probably easier just to call him by name and explain that is your granddaughter's husband.
Your grandmother's sister-in-law is your great aunt and your grandson's great great great aunt.
Yes, you are related to your brother-in-law's grandson. Your brother-in-law's grandson would be your nephew once removed. This means that you are not directly related by blood, but you share a family connection through your brother-in-law's family.
what are grandparents changes of getting grandson age when daughter is sleeping with father in law
There is no relation between you and your grandmother's cousin-in-law's grandson.
Your sister-in-law's grandson is your great nephew.