Walker also is studying Nicky Freeman. Like Gabby, he was born blind and was close to death for a few months. When he was 1 year old, Nicky said his first words: "Mommy," "Daddy" and "Teddy." But at 14 months old, he mysteriously stopped talking and hasn't spoken since.
His mother, Kayleen Freeman, said one of her friends asked, "Does that mean if he is going to be in his 70s, he'll really be 280?"
Freeman told filmmakers that she was convinced her son understands things, because he will pick up conversations and "burst into laughter." He loves music, "loud and fast," and talks with his body language.
"He really loves having a massage," she said. "He comes over to me and shows exactly where he wants his back rubbed."
Even though Nicky has not grown beyond the size of a grade-school student, he has a voracious appetite, eating twice what an adult eats, according to his mother.
The same holds true for Gabby.
"It doesn't matter what her nutrition is," said her mother. "She doesn't get bigger."
The Williams family met the Freemans when they came to the United States to consult with Walker.
"It was great," said Williams. "I think Nicky has a lot more abilities than Gabby. He walks and I don't know if she will get to that point. But talking with his mother, there was a connection for me."
Raising a perpetual infant is tiring. There always are two infant seats in the car -- one of the latest baby and one for Gabby.
Some people think Williams has twins. But, she said, "Like everything in life, you learn to do what you've got to do."
On top of caring for Gabby, Williams has worked in a doctor's office continuously throughout the birth of all her children. Her employers have been flexible, allowing her to work most days from home.
The hardest part is listening to Gabby cry and not knowing why.
"That's hard for a mom," Williams said. "Not knowing how to fix it."
But Gabby's ability to connect with people "without even saying a word" is gratifying, according to her mother.
"It's always the most beautiful thing to see Gabby and how she touches strangers' lives," said Williams. "Whenever we are in public, they stop because of her hair -- how much she has. I tell them she's only 6 and we have a discussion.
"I always say I have come to a peace with Gabriel," said her mother. "For a long time I was waking up in the night, thinking I would get up and she wouldn't be alive anymore. But we are Catholic and put our faith in God. Gabby is God's child and he will take care of her."