An insider tells E! News that the betrothed royal has already asked William to be his best man when Harry and Meghan tie the knot at St. George's Chapel at Windsor Castle this May.
The source adds that Kate Middleton will not have a role in the nuptials, as she will have her hands full with three children (she's due to give birth in April) and plans to stay in the pews for the ceremony.
Speaking of children, the insider informs E! News that Harry's niece and nephew, Prince George and Princess Charlotte, will have roles on the day of the wedding, as will Isabel Veronica Mulroney, the daughter of Meghan's best friend Jessica Mulroney and husband Ben Mulroney.
Traditionally, there isn't a "best man" at a royal wedding. Instead grooms have "supporters." Prince Charles asked brothers Prince Andrew and Prince Edward to be his "supporters" when he married Princess Diana in 1981.
However, Prince William broke with tradition and had Harry be his best man when he married Middleton in 2011. Kate's sister Pippa Middleton served as maid of honor.