Princess Eugenie grew up on the Windsor grounds, and she convinced Harry and Meghan that it was a great place for a peaceful childhood.
"And Louis is getting bigger".
"She is quite opinionated and Harry has got very dictatorial of late, which hasn't made things easy at times", one source told The Daily Mail on Sunday.
"Yeah, absolutely. It's such a special time to have little kiddies and a cousin for George and Charlotte and Louis!"
Despite their big move next year, the Duke and Duchess of Sussex will still maintain primary offices in Kensington Palace although Harry and William, second in line to the British throne, will conduct their royal duties from separate offices.
There are hardly any details from inside the soiree, but there are some lovely pics of Kate and Meghan taken through their vehicle windows.
The Duchess told one member of the crowd: "They're getting excited for Christmas time because they've started all their Christmas songs and Christmas trees are going up".
Hollywood's A-list couple George and Amal Clooney are reportedly among the godparents of Prince Harry and Meghan's first-born child. Plenty of British tabloids-and some US publications-assumed the means behind the couple's decision to relocate may be related to Harry's changing relationship with his big brother Prince William.
The source added that the tension is not the reason for their move.
Amen to that! But maybe it's also, ya know, enflaming mild tensions between Kate and Meghan, by proxy?!
Meanwhile, Harry and Meghan are set to leave Kensington Palace for a new home in Windsor. "Understanding the Palace way, the deference, the politics and the fact that there's a pecking order, is taking a while for Meghan to get her head around".