Captain Dara Fitzpatrick was "a wonderful mother" whose "happy, contented and unstressed" three-year-old son is a tribute to her, the helicopter pilot's sister has said.
Niamh Fitzpatrick described how Dara had adopted her son at the age of one week old and managed to juggle weaning, potty-training and early child-rearing with a job that was "not 9 to 5".
The psychologist said Dara had figured out a system whereby she was able to work demanding 24-hour shifts while raising a child with the help of her family, particularly her sister Eimear who had lived with her.
"We now know how she wants to have Fionn raised. We know, we don't wonder," Niamh said.
"To have this little boy who is singing, laughing, happy and contented to be with us. He is not stressed or bothered.
"He had people coming through his house, he had four-and-a-half hours in a car in the drive to Belmullet, in a hotel overnight and we were walking him around the hospital because we didn't want him coming into the morgue - and yet he is okay. That a tribute to a girl who is a great mother," she said.
"Professionally she was a kind and lovely girl, but I also want to say what a great mother she is. That she has a little boy who is handling this."
As a psychologist, Niamh is consulting with colleagues on how best to help Fionn deal with the loss of his mother. "He lost his birth mother - and that is a loss. And now he's also lost his adopted mother and all before the age of three years old," she said.
Yesterday, Capt Fitzpatrick's family told how 39 years ago, they tragically lost another child on the exact same day.
Capt Fitzpatrick's parents, John and Mary, spoke of their previous experience of losing a child, and praised their daughter's courage.
When asked where she got her strength from, her sister Niamh responded: "From the two people standing beside me."
"Thirty-nine years ago, my parents had a stillborn, and on the same day, 39 years apart, they have now lost two of their six children," she said.
Her parents described Capt Fitzpatrick as being "beautiful, inside and out".
They spoke of how they stayed with her last night to make sure she wasn't alone. "She always told us if anything ever happened, she never wanted to be left alone, so when we arrived down here last night we decided we would do shifts.
"We kept our promise to her."