Would this be their second cousin once removed?
So, a kid's great-grandfather had a wife who gave birth to a different kid. The grandfather divorced her, got another wife, and had the great-grand kid's father. Then the kid from the different wife has a kid.
What would be the relationship be called between the great-grand kid and the kid from the other wife's son?
A guy has a wife. They have a kid we'll call Jeff. They get divorced. The guy gets another wife and has a kid we'll call Nick. Nick has a kid named Bob. Jeff has a kid named Tom.
What is the relationship between Bob and Tom called?