Kate Middleton and Prince William may have asked Meghan Markle to be a godmother to their third baby.

The new addition to the Duke and Duchess of Cambridge's family will arrive in April. And according to an insider, Prince William and Middleton have reportedly decided to ask Prince Harry's fiancée to be one of the godparents to their upcoming baby.

"They've already formed a strong sisterly bond, and it's Kate's way of showing how close they've become," a source told Woman's Day.

When the "Suits" star's romance with Prince Harry was publicized, Markle was often compared to Middleton. However, despite the rumored rivalry, the two women have apparently maintained a special friendship.

In fact, during Prince Harry and Markle's first joint interview following their royal engagement, the Duke recalled how Prince William and Middleton were "longing" to meet the actress. Markle also said that the Duchess of Cambridge was "wonderful," which seemed to hint at their good relationship.

In addition, Markle and Middleton will be neighbors when the latter officially becomes a royal after her wedding to Prince Harry. The mom-of-two is expected to be her mentor.

"Kate knows how difficult it is navigating one's way through this very different world. [And] it was important to [Harry] that Meghan and Kate got to know each other, as she has experienced many of the challenges Meghan now faces," an insider told E! News. "Catherine did it and so they know it's possible for an outsider, without any prior interactions with the establishment, to integrate well. Catherine is very aware that Meghan will need a friend alongside her while she gets used to the way things are done around here."

But while Markle has a chance to be one of the godparents of Middleton and Prince William's third baby, Prince Harry will still not be part of the list. Initially, royal family members choose the baby's uncle to be one of the godparents, but the Duke and Duchess of Cambridge have skipped Prince Harry when they selected godparents for Prince George and Princess Charlotte.

According to Richard Fitzwilliams, Prince William and Middleton picked the godparents of their children from their close circle of friends. Meanwhile, Princess Beatrice and Princess Eugenie could possibly be godmothers as well.