Your brother-in-law's brother. Though many will refer to them as a brother-in-law, they technically are not related to you.
grandma in law.
By their names. They are not in laws
Your brother-in-law's wife would be your sister (in law), which means that she would probably be related to you (unless either of you were adopted).
Generally, they would be referred to as "in-laws" as a generic term. Or, alternately, as "our daughter's in-laws". In person, you would introduce them as "our son-in-law's parents".
If your brother adopted you, you are his son or daughter and his in-laws are your grandparents by adoption.
Your mother's brother is your uncle. Your father is his brother-in-law but he could also have other brothers-in-law. These would be men married to his other sisters, or the brothers of his wife. If they are men who married his other sisters, they are your uncles. If they are brothers of his wife, they are not related to you.
There would be no relationship as you do not share a common ancestor. If your brother-in-law is married to your sister, then her daughter is your niece, her husband would be referred to as your niece's husband.
No, there is no relationship between the two of you.
If your brother-in-law's daughter is by your sister, she is your niece. If your brother-in-law's daughter is by someone else, she is genealogically not in your family tree.
great uncle inlaw
Your daughter-in-laws sister. There is no relationship as you do not share a common ancestor.
There is no genealogical relationship. He is just your son-in-law's brother.
There are no US laws prohibiting brothers and sisters from sharing a room.
Yes, you are only related by marriage. There have been marriages of sisters who marry brothers.
Not at all. There are many men and women who date and consequently marry the siblings of their brother-in-laws and sister-in-laws. Some folks may find it strange to "keep it in the family", but there are many success stories of this nature. Technically, your brother or sister's in-laws are not YOUR in-laws, and you have no real legal relationship to them. If my fiancee had a nice brother for me to set my younger sister up with, I'd go for it in a heart-beat.
You are brother in laws.