How It Happened
Chrissy wanted to be a surrogate for her sister. She went to get two of Annie’s embryos implanted, and Annie went along. As luck would have it, Annie was also at the right point in her cycle, so the doctor implanted two of Annie and Joby’s embryos inside her, too.
The sisters didn’t know if Annie’s pregnancy would take, so they decided to keep it hushed until they were sure.