In-laws

When you marry, your husband (or wife's) family become your in-laws. The mother of your spouse (husband or wife) is your mother-in-law and his or her father becomes your father-in-law. The term in-law is also used to describe your relationship with the spouses of your siblings. So the husband of your sister becomes your brother-in-law, while the sister of your husband becomes your sister-in-law. If you are a woman, you become the daughter-in-law of your husband's parents, and if you are a man, you become the son-in-law of your wife's parents. The same term in-law is used for all generations. The husband of your aunt is still your mother's brother-in-law, for example.

Grandparents / grandchildren

The parents of your parents are your grandparents – grandmother and grandfather. You are their grandchildren – either a granddaughter or a grandson. If your grandparent has a sister, she is your great-aunt. If your grandparent has a brother, he is your great-uncle. (And you are either his or her great-niece or great-nephew.)

The mother of your grandmother or grandfather is your great-grandmother. The father is your great-grandfather. If you go back another generation, the grandmother of your grandmother / grandfather is your great-great-grandmother. The grandfather of your grandparent becomes your great-great-grandfather.