Your nephew-in-law. Just like your sister's husband is your brother-in-law, i.e. has the same type of relationship to you (except for being male) that your sister has, only it is "by law" (marriage) not "by blood" (Biology). Interestingly, your brother-in-law's son would also be your nephew-in-law, and your brother-in-law's daughter's husband would be too.
There is none. "This is George, my niece's husband." In most families he would referred to as a nephew.
He is their Uncle and they are nieces and nephews.
You would be a first cousin by marriage, in other words, there is no direct relationship between you.
Your sister's husband is your children's uncle. They are his nieces and nephews.
Your husband's nephew is also your nephew, and you are his aunt. Remember that if your father has a married brother, the brother is your uncle and the brother's wife is your aunt , with no mention of one being related by marriage and the other not. They are simply your aunt and uncle. The same applies to your relationship to your husband's sibling's children. You are simply their aunt.
You do not have a niece-in-law. Some of your nieces and nephews are that because they are the children of your husband's siblings. They are your nieces and nephews and you and your husband together are their "aunt and uncle."
Your brother's children would be your nieces and nephews.
Your niece is the daughter of your brother or sister. That relationship is not ended by divorce. If your brother married a woman who already had a daughter (from an earlier marriage), then she would be your "step-niece", and this relationship would, technically, be ended by a later divorce.
Your sister's husband is your brother-in-law. Your brother-in-law's brother is not related to you and neither are his children. But he is your sister's brother-in-law and his children are your sister's nieces and nephews.
A husband's niece is the daughter of his brother or sister. A wife's niece is the daughter of her brother or sister. In general, the two nieces are not related to each other.The only way the two nieces could be related would be if the husband and wife were related in some way in addition to their relationship through marriage, for example, if they were also cousins to each other.
They are your nieces and nephews.
Hera had a very strained relationship with her husband.