Anias, left, and Jadon McDonald were born conjoined at the head, something only seen in 1 out of every 2.5 million live births. They were separated in a 27-hour surgery at the Children's Hospital at Montefiore Medical Center in New York in October. Krisanne Johnson/Verbatim for CNN

Nicole and Christian McDonald talk with Dr. Sanjay Gupta in the family waiting area on October 13 as a team worked to separate Jadon and Anias. "When we sent them off this morning, to me, I felt at peace with it and just ready to handle what comes after," Nicole said. Krisanne Johnson/Verbatim for CNN

Dr. James Goodrich Goodrich, left, leads a surgical team as they prepared to separate the twins. "Failure is not an option," Goodrich told the team as they got started. Krisanne Johnson/Verbatim for CNN

The twins' surgery was Goodrich's longest craniopagus surgery. It's meticulous, tricky and complex: A single cut too deep can lead to catastrophic bleeding. Krisanne Johnson/Verbatim for CNN

Goodrich's team worked more than 16 hours just to separate the boys, and each continued surgery individually afterward. Krisanne Johnson/Verbatim for CNN

Newly separated twins Anias, left, and Jadon in surgery at the hospital. Goodrich informed the family of the successful separation at about 3 a.m. October 14. "Well, we did it," he told them. When it was official, the room burst into spontaneous applause.

Krisanne Johnson/verbatim for CNN

Jadon recovers in the pediatric intensive care unit shortly after the surgery. Krisanne Johnson/Verbatin for CNN

Anias returns to his room after his head dressing was changed. Krisanne Johnson/Verbatin for CNN

Jadon stretches his arms in his room within the hospital's pediatric intensive care unit. Anias rests in a nearby bed in the same room. Krissanne Johnson/Verbatim for CNN

Anias, left, stares at Jadon for the first time since the surgery that separated them. Courtesy Chris Grosso

Nicole McDonald, right, and her mother, Chris Grosso, with Anias in mid-November. Anias had to have his skull cap removed due to infection, but doctors say they are still pleased with his recovery. Krissanne Johnson/Verbatim for CNN

Anias, left, and Jadon lie in a red wagon at the Children's Hospital at Montefiore Medical Center on December 13 as they prepare for the next stage of their journey, two months after their surgery. Mark Kauzlarich for CNN

The family was headed to the hospital's banquet hall on December 13, where surgical and pediatric intensive care staff members were gathered for a farewell party. Mark Kauzlarich for CNN

Dr. Oren Tepper, the twins' lead plastic surgeon, holds a thank you gift from the McDonald family presented to him at the farewell party. Mark Kauzlarich for CNN

Nicole McDonald holds Anias as his twin brother, Jadon, sleeps in the bed to the left. The twins' older brother, Aza, watches television at the hospital from one of the boys' beds shortly before they left for rehab. Mark Kauzlarich for CNN

Jadon, left, and Anias McDonald look up at hospital staff as they leave their room at Montefiore Children's Hospital in New York. Their older brother, Aza, proudly sits at the front of the wagon. It was mid-December and they were headed to rehab. Mark Kauzlarich for CNN

Nicole McDonald pushes a stroller with Anias as her husband Christian pushes Jadon down a hallway on June 14 at Blythedale Children's Hospital in Valhalla, New York, where the boys have been rehabilitating. Mark Kauzlarich for CNN

Anias plays with a toy while laying on a mat in his room at Blythedale Children's Hospital. Mark Kauzlarich for CNN

Jadon eats small snacks and drinks from a sippy cup on his own, major progress since he first moved to rehab. Mark Kauzlarich for CNN

Nicole McDonald plays with her son Anias as Christian McDonald holds Jadon on a playground outside Blythedale Children's Hospital. Mark Kauzlarich/30207334A/Mark Kauzlarich for CNN

Nicole McDonald holds Jadon while looking over discharge information on September 1, as they prepare to leave the rehab facility and head home as a family for the first time. Mark Kauzlarich for CNN

Nicole McDonald takes Anias into the family's new house for the first time with his older brother, Aza. Mark Kauzlarich for CNN