While regular grandparents have to go through the courts if they want custody of their grandchildren, the king has automatic legal custody of all his descendants and minor grandchildren.
The monarch has legal custody of his grandchildren, royal historian Marlene Koenig told News.com.au. in 2018.
This means that Charles technically has custody of Prince William and Kate Middleton’s three children, Prince George, Prince Charlotte and Prince Louis, and Meghan Markle and Prince Harry’s children Archie and Lilibet.
This 300-year rule may seem strange, and while it’s unlikely the king will ever take his grandchildren from their parents, technically the law still stands.
Source : www.insider.com