What is the family relationship between Princess Margaret and Prince Harry?

Princess Margaret ( no longer living) was the sister of Queen Elizabeth. Princess Anne is I believe a daughter of Elizabeth II. Therefore she ( Margaret) would have been an aunt to Princess Anne. It is like Anastasia"s Aunt Betty- who was the sister of Czar Nicholas. oddly Aunt Betty does not appear in the l997 cartoon film-possibly as she was brutally murdered by the N.K.V.D. men. I understand she was tossed- LIVE down a garbage disposal chute on the ourskirts of St, Petersburg. the pits indeed!