Your sister's husband is your father's son-in-law.
Your son's wife's father is your son'sfather-in-law. There is no term in the English language for a familial relationship between you and your son's father-in-law. Put more simply, the two of you are not related.
You can call her by her first name or if your comfortable some son-in-laws call them mom.
The girl's father-in-law is the father of her spouse, while her spouse's father-in-law is the father of her spouse's spouse. Therefore, the girls's father-in-law is also the son of the boy's father-in-law.
You have no socially named relationship to your step-great-grandson-in-law's father. If you like, you might call him "son" or "Mr. ...." or simply call him by his first name.
The son of a father's son is commonly referred to as a grandson.
Your father's brother's son is your first cousin.
Either: Albert's son is my husband and and father of my son, Albert is my father in law. Or: If Albert's son is me, the father of my son, then Albert is my father.
Your father-in-law's son is either your brother-in-law or your husband.
Your father's brother's son is your first cousin.
Your son-in-law is your daughter's husband.
The house of your father-in-law is your father-in-law'shouse.