In the sense of what is the name of the relationship, that would be "second cousin-in-law", though if you are that close to your second cousin and his wife, you could just say, "cousin".
In the sense of how you would address her, it would be the same as with your second cousin. Just the name that she goes by. After all, "second cousin", or even "cousin", isn't a title like Uncle or Aunt is.
Your brother's wife's cousins are not related to you and the English language has no special term for that. The same applies to the cousins of a stepbrother's wife.
If the children of your great uncle's wife are also your great uncle's children, then they are your parent's first cousins, and your first cousins, once removed.If your great uncle's wife has children from a previous marriage, they are not related to you because you have no common ancestor. However, if they were very young when their mother married your great uncle, it may be convenient to treat them like "members of the family" and call them your first cousins, once removed.
They are out of synch by a generation. They would be first cousins once removed.
You are not related to the wife of your first cousin once removed, or of any other cousins. If you need to refer to her other than by name, call her "the wife of my first cousin once removed," of, more simply, "my cousin's wife."
If you are close to your step-brother, or to his wife, you can call her your sister-in-law. If you are not close, you can call her your "step-brother's wife."
The children of your wife's first cousin are her first cousins, once removed. They are not related to you.
Most students never call their first cousins and some don't event know who they are.
If your daughter is also your wife's daughter, your daughter and your wife's first cousin are first cousins, once removed, otherwise they are not related.
In genealogy terms she would be "spouse of your first cousin."
Your baby and your cousins are first cousins once removed to each other. You baby and your second cousins are second cousins once removed to each other.
This is if you are first cousins. They would be your first cousin once removed. Since the child of your cousin is a generation away from you they are the once removed.
Ellen Cousins