Friends and family of Marie King and Kelly Boren will hold an event to remember their lives.
The mother and daughter were shot dead in Utah, United States by Kelly’s police officer husband, who also murdered the couple’s two children then shot himself.
Kelly was born in Northampton but went to the United States when only months old with mother Marie and her father, who was in the American air force.
Marie’s family said today she still kept in touch with many friends in Northampton, having lived in the town centre, Spencer and most recently Abington.
Marie’s sister, Jeanette Malpas, said: “They were just a fun-loving family, and Marie had lots and lots of friends in Northampton still who she kept in touch with on Facebook and things.
“We just can’t get our heads around it - why it happened - but you’ll never know the reasons why.
“We are all devastated.”
A memorial event, which will include a balloon release, will be held at the Queen Eleanor Pub in Newport Pagnell Road, from 6pm on Wednesday January 22.
Mrs Malpas said: “She knew a lot of people here who won’t be able to go to America so we are holding something in Northampton.
“Marie wasn’t religious so there’ll be no church service here.
“It’s so people can pay their respects and friends and family can say goodbye.”
According to Spanish Fork police in Utah, United States, officers visited a home for a welfare check after a man living there failed to arrive to work.
Investigators said they believe the male resident, identified as Joshua Boren, 34, killed his four family members and then took his own life.
Among the four victims was Kelly Boren, 32, who was born in Northampton.
Also found were her children Jaden Boren, 7, Haley Boren, 5, and Kelly’s mum Marie King, 55, who was a former Northampton School for Girls pupil.
Investigators said Joshua and Kelly had been experiencing marital problems for the past several months. They said no suicide note was found in the home.