The Weasleys have a magical clock in their home, The Burrow. It doesn't tell the time, but rather tells where and how the Weasley family members are.
Mrs Weasley glanced at the grandfather clock in the corner. Harry liked this clock. It was completely useless if you wanted to know the time, but otherwise very informative. It had nine golden hands, and each of them was engraved with one of the Weasley family's names. There were no numerals around the face, but descriptions of where each family member might be. 'Home', 'school' and 'work' were there, but there was also 'lost', 'hospital', 'prison' and, in the position where the number twelve would be on a normal clock, 'mortal peril'.
— Harry Potter and the Goblet of Fire, Chapter 10: "Mayhem at the Ministry", by J.K. Rowling
Are spouses represented on the clock as well? In the main 7 books, we see the marriage of Fleur Delacour to Bill Weasley and are informed of the marriages of Hermione Granger to Ron Weasley and of Harry Potter to Ginny Weasley.
Not only that, but Molly and Arthur have grandchildren as well. Victoire, Dominique, and Louis through Bill and Fleur, Molly and Lucy through Percy and Audrey, Fred and Roxanne through George and Angelina, Rose and Hugo through Ron and Hermione, and James, Albus, and Lily through Ginny and Harry. Are they all represented on the clock as well?
It seems that family members' hands aren't removed from the clock after they move out, since Bill and Charley were still represented even though they no longer lived at The Burrow.
So what are the criteria for inclusion on the clock?