Your first cousin's niece is the daughter of her brother or sister. Your first cousin's brothers and sisters are also your first cousins. So your first cousin's niece is the daughter of your first cousin and is therefore your first cousin, once removed.
Your niece and your daughter are first cousins. Your daughter and the daughter of your niece are first Cousins, once removed.
Yes, of course your son and your great niece are related. They are first cousins, once removed, to each other. (Your great niece's parent, your niece or nephew, and your son are first cousins to each other.)
Either they are second cousins or technically not related at all. Your cousin's niece would be one of her siblings' children, in which case it would one of your cousin's daughters, or her spouses' niece, in which case there is no blood relationship, but most families would refer to them as a cousin.
They are first cousins.
Your grandchild and your niece are first cousins, once removed.
Your niece and your daughter are first cousins to each other.
Your son and your niece are first cousins. Her daughter and your son are first cousins, once removed.
AnswerNo. They are not related--if this is what you mean...If your father has a nephew, and your mother has a niece...you are related to BOTH of them (1st cousins). However, they are not related to each other (unless, of course, your parents themselves are cousins...etc.)
Your grandchildren and your great niece are second cousins to each other.
Your daughter and your niece's daughter are first cousins, once removed.
Great nephew. Your children are the first cousins of your niece and your children would be first cousins once removed. Your grandchildren and your niece's child would be second cousins.
Most likely they would not be related to you