A California mom had to fight for custody of her biological child when she became pregnant with "twins" while acting as a surrogate for a Chinese couple.

Jessica Allen was already a mother of two when she decided to become a surrogate to Mr. and Mrs. Liu. The $30,000 she would earn would help her become a stay-at-home mom, and to buy a house. She underwent in-vitro fertilization in April 2016. Allen says she and her partner, Wardell Jasper, also had sex--with a condom--after getting permission to do so from the IVF doctor. When she went to the hospital, doctors told her she was pregnant with twins.

"Not once during the pregnancy did any of the medical staff provided by the agency say that the babies were in separate sacs. As far as we were concerned, the transferred embryo had split in two and the twins were identical," Allen tells the New York Post.

When the babies were born by C-section in December, Allen says the babies were taken from the room before she could even see them. The next morning, she says, the babies' mother visited her in the hospital and showed her a photo on her cell phone.

“Wow! They look different,” Allen says she told her, before she snatched back the device.

Allen says she had hit the nail on the head. DNA tests confirmed that the boys were not actually twins.

"It turned out that, in an extremely rare medical incident called superfetation, we had gotten pregnant naturally, despite using condoms, after the in vitro fertilization (IVF) cycle during which Mr. and Mrs. Liu’s embryo was transferred into my uterus," she says. "Mike was a biological match to the Lius, while Max had my genes." (The names of the babies and the couple were changed for this story.)

But then, things got worse. Allen says she was told that the Lius didn't want to keep Max, and the agency they had used had someone caring for the baby. Not only that, but the agency was essentially shopping around for couples to adopt Max and cover the cost of the compensation the Lius were now demanding as "compensation." The Lius were also considering putting the baby up for adoption, she says.

Allen and Jasper hired a lawyer to help, and through negotiations, they got their biological son back--and the agency agreed that the "fees" the couple owed would be zero.

A worker from the agency met Allen at a Starbucks and gave her her baby, which the couple have now renamed Malachi. She says he's happy, learning to walk, and loves his big brothers.

"Wardell and I, who got married in April, weren’t planning to expand our family so soon, but we treasure Malachi with all our hearts. I don’t regret becoming a surrogate mom because that would mean regretting my son. I just hope other women considering surrogacy can learn from my story. And that a greater good will come out of this nightmare," says Allen.