The family are devastated by the loss of their "beautiful daughters" in an accident that happened in minutes.
The tragedy unfolded just after the family had finished lunch. When the girls went to play outside but could not be found, Young and husband Troy started searching for them.
Aige found his younger sisters in the pool soon after. Their parents frantically tried to revive the pair before paramedics arrived, but they were unsuccessful.
"We know (they are) at rest, they're at peace, they're not going to go through any pain, they're just sleeping," Young said.
Even as she grappled with the devastating events, Young said she wanted to thank the emergency services personnel who tried to save her children.
She said she was thankful for the support from friends and family as news of the deaths spread.
"We had people that we haven't even known very well ... just start breaking down and crying," she said.
Police are not treating the incident as suspicious but detectives and Logan City council inspectors spent the afternoon trying to determine how the pair were able to enter the pool area. Police took statements from Aige and both parents.
Family and friends gathered outside the home yesterday to support the parents and the other three children.
Young's sister-in-law Tamara Sengstock told The Courier-Mail that the family was shattered.
"They were beautiful little girls with a whole life ahead of them," she said.
"They had big hearts and loved everyone. They always were protective of each other.
"Renise and Troy are absolutely distraught and are trying to hold themselves together for her 5-year-old son, 1½-year-old daughter and few-months-old daughter."
- The Courier-Mail
