A British woman gave birth to her brother’s baby last week after volunteering to be his partner’s surrogate — making her both the mother and the aunt of their child.

“We are blown away by the strength, heart and courage of Chapelle and will never be able to truly thank her for bringing us our perfect little bundle,” wrote Michael Smith on Facebook following the birth of his daughter, Harper Elizabeth Smith. “We love you more than you know!”

Smith and Chapelle Cooper’s brother, Scott Stephenson, told Yahoo Style UK that they had been on the fence about using a surrogate and were afraid they wouldn’t be able to find someone they could rely on.

After some consideration, Cooper apparently threw her name in — and their little family was formed.

“We found ourselves really protective of her throughout the pregnancy.” Smith said.

Cooper delivered little Harper last Friday — 15 days earlier than expected. Her egg had been used with Smith’s sperm to conceive her.

“Welcoming Harper Elizabeth Smith to the world,” wrote Cooper on Facebook. “15 days early, 5lb 8 and so beautiful! Congratulations to Scott Stephenson and Michael A D Smith, can honestly say they were amazing in the delivery room, they gave so much love and so much care to me and to Harper, cannot thank you enough. Enjoy your new family life, I love you all so much.”

The new mother — and aunt — told Yahoo that she wants to be a “big part of Harper’s life” but not as her parent. She and Stephenson plan to tell her truth when she grows up, however, they’ll be treating her as Cooper’s niece.

“I don’t think I could’ve done it if I’d never seen her again,” Cooper said, “which made it a lot easier.”

Describing his “selfless” sister, Stephenson told Yahoo: “Who can say they’ve done that for somebody else. It’s the most selfless and amazing gift.”