The touching story about her oldest son Mark was just one of the poignant tales that prompted both tears and laughter at the emotionally-charged Month's Mind Mass.
Three generations were lost to the waters of Lough Swilly in the horrifying Co Donegal tragedy last month.
Louise lost her partner, Sean McGrotty (46), their two sons, Mark (12) and Evan (8), her mother Ruth Daniels (57) and her sister Jodie-Lee Daniels (15) when their car slid off a slipway.
Among those gathered with the two families was Davitt Walsh, the man who heroically rescued baby Rioghnach-Ann, Louise and Sean's four-month-old daughter and the sole survivor of the tragedy.
Fr Paddy O'Kane, who has provided spiritual support to the McGrotty and Daniels families for the past month, was joined at the alter by Bishop of Derry Donal McKeown.
In a touching and heartfelt homily, Fr O'Kane recalled "happy-go-lucky" children who loved Derry City Football Club - but not as much as their mum.
"Mark loved playing at school, or on the street with his friends," the priest said.
"He would run inside and give Louise a hug and then re-join his friends - for Louise had told him and Evan to come and hug her as often as they wanted."
He said Evan, who had Muscular Dystrophy, showed great determination in his short life. "Once he was ill and was told he had to stay at home - but he rebelled and insisted he would go," Fr O'Kane said. "You can see the certificate of merit he got for 100% attendance that year."
Fr O'Kane also held up a religious statue Evan had admired for the congregation to see in the Ballymagroarty church - where the boy was due to have first Holy Communion in a few weeks. "He loved this little statue of Our Lady so much that he broke her hand with his hugs and kisses," he added.
The priest said that Louise and her family had given him the "greatest privilege" by "accepting my shoulder on which to shed your tears".
He said: "I have had letters and phone calls from good people from countries near and far, asking me to tell Louise and her family that they are thinking about them and praying for them. There have been Books of Condolences from people of many faiths. We have all been united in grief, and you, Louise, have told me to pass on your deep gratitude to all, and how it has helped in some little way to come to terms with all that has happened."
Fr O'Kane said Ruth "doted on her six children and eight grandchildren".
He recalled Jodie-Lee's big smile and infectious laugh and how she was loved by everyone and "had made a great contribution to the life of the school" and how like her mother she "loved her style".
Louise's partner Sean was "a hard grafter" who was at the top of his profession as a glazier, said Fr O'Kane.
Later, Bishop Donal McKeown paid tribute to Fr O'Kane, sparking applause from the congregation and tears from the priest.