Depends on the laws where you are and the arrangement with the uncle.
Your uncle's sons and daughters are your first cousins.
well my moms uncle is my uncle too. so it would be the daughters uncle also.
Uncle
To your sister's daughter you are an aunt (or uncle) and she is your niece. To your niece's daughter ( your sister's granddaughter) you are a great-aunt (or great-uncle) and she is your grand-niece.
rachel and rebeca
If you have no siblings but your daughter has an uncle, he is the brother of your spouse, your brother-in-law.
Your uncle through marriage is the husband of your aunt, the sister of your father or mother. All of your aunt's nieces (the daughters of her siblings) are also his nieces. So you (if your are female) and our sisters are nieces of your uncle through marriage, as are the other daughters of the siblings of your parents.Also, your uncle through marriage has nieces who are the daughters of his bothers and sisters. They are not related to you because you do not share any ancestor with them.
You!
2 daughters and 2 parents a uncle a aunt and a grand parentas
You would be his Great Uncle or Great Aunt He in turn would be your Great Nephew.
in the movie Uncle Buck, there are actually two daughters. Tia is played by Jean Louisa Kelly. And young Maisy is played by Gaby Hoffmann
Your daughter's uncle can be your brother. Her parent who is not your sibling (your brother-in-law or sister-in-law) could also have brothers. They will also be your daughter's uncles, but will not be related to you.