Kate Middleton is currently on maternity leave, since the birth of Prince Louis in April, but the mum might have to miss Princess Eugenie's for a whole different reason...
The mum-of-three attended Harry and Meghan's wedding back in May, just weeks after welcoming her third child.
Now there's another big royal wedding coming up, which will be held at the same location, and there might be a good reason Kate could have to give it a miss.
Princess Eugenie and Jack Brooksbank, who announced they were engaged earlier this year, will happen on 12 October this year. However, there's another big event happening on Kate's side of the family at about the same time - the birth of her sister Pippa's first child.
There's no doubt that the two Middleton sisters are close, with Pippa having been spotted driving to Kensington Palace the day after she gave birth to Louis.
If Kate wants to be there for her sister and offer her the support and advice only a big sister who has kids of her own can give, then she could have to opt out of the royal nuptials.
The expectant mum announced she was through her first trimester in June, and despite her not revealing the due date, it's expected she could give birth in October - around the same time Princess Eugenie will be saying 'I do'.
She said at the time, in a column for Waitrose magazine: 'I was lucky to pass the 12-week scan without suffering from morning sickness. This being my first pregnancy, I had so many questions I felt were still unanswered.'
If the Duchess of Cambridge does decide to forgo the nuptials to be by her sister's side, it's unclear if her little ones would attend the wedding just with dad William.
While it's an unconfirmed rumour, it's been reported Prince George and Princess Charlotte will once again step up to their pageboy and bridesmaid roles.
They were part of the royal party at Harry and Meghan's wedding in May, but at the time they had their mum by their side to help keep them in check - maybe this time William can do it?
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