Tim: Dad, you keep talking about family in New Zealand. Who are they?
Dad: Well, that's your uncle Bill, his wife and two of their daughters.
Tim: Is uncle Bill your brother?
Dad: No, your uncle Jack is my brother, Bill is my brother-in-law, your mom's brother.
Tim: So his two daughters are my cousins?
Dad: That's right, Sarah and Jane are both your cousins although they are step-sisters.
Tim: What are step-sisters?
Dad: Sarah is your uncle Bill's older daughter. When she was young, Bill's first wife, Sarah's mom died. Three years later Bill married again.
Tim: So uncle Bill's wife is Jane's mother but not Sarah's mother. Right?
Dad: Yes. She is Sarah's step-mother.
Tim: And when are they coming to visit us?
Dad: They want to travel to Europe next year, and will visit us at the same time.