"He bought camping stuff from Kmart apparently and camped out for the night with his baby and his wife," Jayden's mother Tracy Lavender told The Daily Telegraph.
The trio were found "safe and well" at Willmot yesterday evening.
"The ambulance ... found there was not one thing wrong with the baby," Ms Lavender said.
"They're young, yeah, they made the mistake of being young ... (Jayden) had a choice to be a proper father and support his child or walk away.
"He chose to be a man and stand by his girlfriend.
"They're good parents."
Ms Lavender said her son had "been there the whole way through the pregnancy".
"He was at the birth and he hasn't moved from her (and) that baby since she was born."
Its understood Jayden and Jenifer found out they were going to become parents on Father's Day. A few weeks later they were engaged and planned to marry before the baby came along.
They couldn't because they were under 16 - despite Ms Lavender declaring she would have signed her consent for them to wed.
The pair live at Ms Lavender's Dharruk home with her two other kids and another 13-year-old.
Jenifer, who Ms Lavender described as "life smart", had previously moved between eight or nine family homes.
"Jenny is a good mum," Ms Lavender said. "I have a child with a disability and she was phenomenal with him"
She said her son had hoped to raise their kid while attending St Agnes Catholic High School at Rooty Hill.
Police have said no one committed an offence so no charges would be laid over the incident.