Prayers were said for the family during a service at All Saints Catholic Church on Wednesday morning.
The honorary consul of Poland in Northern Ireland, Jerome Mullen, said he had never experienced such a tragedy in his 18 years in the job.
PSNI Supt William Calderwood said emergency services were met with a “shocking scene”.
Police have said the cause of the deaths has not been formally established and they are not seeking anyone else in relation to the deaths.
At a press conference on Tuesday afternoon, Calderwood said they were keeping an open mind, but they were working on a “strong hypothesis” of a “double murder followed by a sudden death”.
He expressed his deepest sympathies to family members, friends and loved ones for their “unimaginable loss”.
Earlier, Sonya McMullan from Women’s Aid told BBC News NI she was “absolutely devastated” when she heard about the deaths.
“Yet another family is experiencing such grief and loss that no family should ever have to go through,” she said.
Women’s Aid has kept track of the number of women and girls who have been killed in Northern Ireland since 2020 and McMullan said this case brings that toll to 31.
“We contribute to the femicide record across the whole of the UK, but it’s devastating having to keep that record and it’s so very important that we remember each and every one of them.”
McMullan said political leaders, the media and members of the public all have a part to play in stopping violence against women and girls.
“This is a call to action that every one of us needs to do more,” she added.
