Just call them Aunt Kate and Uncle William!

Kate Middleton and Prince William are set to meet their nephew, Archie Harrison Mountbatten-Windsor, for the first time on Tuesday. 

Little Archie was born Monday, May 6, about a week past his due date. 

New parents Meghan Markle and Prince Harry spent Mother's Day weekend celebrating their newborn son. The Duke and Duchess shared a sweet picture of baby Archie's feet on Instagram, along with a tribute to mothers "past, present, mothers-to-be, and those lost but forever remembered."

"We honor and celebrate each and every one of you," the post added. 

Kate and William having been traveling for various royal duties over the past week, launching a sailing race last Tuesday and visiting North Wales on Wednesday. 

But they said they were thrilled for Meghan and Harry, and couldn't wait to meet Archie. 

"It’s really exciting for both of them," Kate said. 

"I’m very pleased to welcome my brother to the sleep deprivation society that is parenting!" William joked. 

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