Devastated Lorraine Gallagher, 36, spoke after her eldest daughter, 15-year-old Shannon, was found dead just six weeks after Erin took her own life.
Thirteen-year-old Erin was found dead at the family home in Ballybofey, Co Donegal, on Oct 27.
At the time, Shannon comforted mum Lorraine as they buried the second-year Finn Valley College pupil.
But just weeks after the heartbreaking funeral, Shannon was found dead in her bedroom in Castlefin.
Last night, Lorraine fought back tears as she paid tribute to both her dead daughters.
“Erin and Shannon were the lights of our lives. They were as close as any two sisters could be.
“We are just devastated by what has happened and we just can’t say anymore. We are all just numb.
“We are lost for words to describe how beautiful they were and what they meant to us.
“We just cannot understand what has happened or why it has happened. There are no answers. We are just being asked for time to grieve and to give Shannon a proper burial.
There is always someone there to listen when you're ready to talk: http://t.co/HWiJ0J6G— spunout.ie (@SpunOut) December 13, 2012
“We are asking people, including the media, to respect our privacy and allow us time to bury Shannon with respect and dignity.”
The girl’s grandfather said Shannon had been missing her younger sister and was wrapping Christmas presents before her death.
“She was on Facebook to my son last night talking, saying she was quite unhappy,” Mr Gallagher told 4FM.
“She found it quite hard that she was wrapping up presents. She said she was missing her wee sister.
“Whatever happened last night when she was wrapping the presents up for her mum and her wee brother and people.
“Then she wrote on Facebook saying, ‘This is the hardest thing I’ve had to do baby doll’. She called her wee sister baby doll.”
The family’s solicitor Patsy Gallagher (no relation) has reiterated the family’s plea for privacy at this time.
“I appreciate there will be a level of media interest but I would appeal to the media to respect the family’s privacy at this time,” he said.
Word of Shannon’s death spread quickly around the twin towns of Ballybofey and Stranorlar, which was the scene of her sister Erin’s funeral.
Both girls were pupils at Finn Valley College.
A crisis management team from the HSE was drafted in to the school yesterday to offer services to children affected by the tragedy.
A spokeswoman said: “The HSE extends its deepest sympathies to the family and friends of the deceased.
“Currently the HSE is liaising with the family in relation to this incident and all supports are being made available to provide assistance at this difficult time.”
Shannon was removed from Letterkenny General Hospital yesterday at 6pm to her home in Ballybofey.
She will be waked at the house and her funeral will take place at 11am tomorrow at St Mary’s Church in Stranorlar followed by burial in Castlefin Cemetery.