It has been almost nine months since conjoined twins underwent surgery to separate their skulls.

Dr. James Goodrich was one of 40 team members that performed the 27-hour surgery on Anais and Jadon McDonald at Montefiore Medical Center.

He says that while the separation was successful, the twins began a new journey, post-operation.

"When they're separated, they have to start all over again," Goodrich says. "They have to learn to hold their heads, they have to learn to sit, learn to crawl, learn to walk. That's the stages they're growing through right now."

The twins are now at a rehabilitation center in Westchester County.

On Friday night, the McDonald family and the doctors will be brought into homes across the country during a special CNN documentary.