A family holding a vigil at the bedside of their five-month-old son have described the Duchess of York as their "rock".
Luke Winston-Jones was born with a rare disorder
Luke Winston-Jones from Holyhead was born with a rare condition and had three holes in his heart.
His family, who have since formed a friendship with the Duchess, were warned he may not survive.
Sarah Ferguson telephones Luke's family twice a week and she sent him her favourite childhood doll called Red.
The toy is kept at his bedside in Ysbyty Gwynedd, Bangor alongside messages from the Duchess and her two daughters Beatrice,16, and Eugenie,14.
The royal sisters have written personal poems to Luke offering their "emotional strength".
The Duchess has explained to Luke's mother Ruth Winston-Jones that the red-headed doll she passed on provided her with courage whenever she had difficulties in her younger years.
Mrs Winston-Jones said Sarah Ferguson and the princesses are a "rock" for the family and have given them great inspiration.
The Duchess heard about Luke's illness, called Edwards Syndrome, when his aunt Jacquie Kirkwood wrote for help in raising the profile of an appeal set up so special medical equipment can be bought.
Within 24 hours the former wife of Prince Andrew had contacted the family.
"She has gone out of her way for us," said Mrs Kirkwood.
"She phones and writes to Ruth and phones the hospital.
"The things that she writes are very personal and private and very touching...she's a good friend now.
"I've got to say she's very emotionally involved with Luke, in my own personal opinion she's been very misunderstood, she's extremely warm and sympathetic to the situation."
Two of the holes in Luke's heart have healed naturally and the family are considering flying a heart specialist from the USA to band the one hole that still remains.
Mrs Kirkwood said the Duchess has promised to "help 100%" and she even has a framed photograph of the youngster on her desk.
Luke's family hope he will be well enough to leave hospital within the next few weeks.