By Alexandra Whittaker
Apr 24, 2018 @ 11:00 am

It's undoubtedly a happy week for the British royal family. Kate Middleton and Prince William welcomed their third child—a baby boy whose name has yet to be unveiled—but the news might not be easy for everyone to hear.

While Prince George is already a big brother, the new royal baby means that for the first time ever, Princess Charlotte is a big sister. And that's something her mom is worried about.

CHRISTIAN CHARISIUS/AFP/Getty Images

“Kate’s worried that Charlotte will feel it the hardest as the youngest, but she’s such a confident little girl and growing up so fast, Kate is hoping she will adjust," a friend of the family revealed to People.

Happily, the source also added that Charlotte and George "are so excited" about the new baby, so hopefully the happiness outweighs any unease.

Even if it doesn't though, their parents seem to have things under control. Having three siblings in the family isn't new to Middleton, who grew up with younger sister Pippa and younger brother James.

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"[She] is one of three siblings, and it’s a good family size," the source said. "Boy-girl-boy is pretty cool as well.” The source added that parenthood “suits [Will and Kate] really well. They are enjoying it and are very happy.”