Her sister dated Prince Charles
There are definitely ways to improve your relationship with your sibling, but we're not sure if sharing a boyfriend is one of them. Before Diana and Charles started going steady, he dated her sister, Sarah. She introduced the two when Diana was just 16 and takes credit for their falling in love, calling herself Cupid.
9 Secrets About Princess Diana No One Knew About Until After Her Death, Source:https://www.rd.com/list/princess-diana-secrets/