The family of a couple and their daughter from Lancashire who were shot dead in Pakistan are due to attend a Parliamentary debate on the deaths.
Mohammad Yousaf, 51, his wife Pervez, 49, and daughter Tanya, 23, were killed at a cemetery near Gujrat on 20 May.
One gunman was killed, one was arrested at the scene and another two went on the run. They are still missing.
Pendle MP Andrew Stephenson will outline the case in an Adjournment Debate later.
More than 100 family members and supporters are expected to travel from the Yousafs' home town, Nelson, to the House of Commons.
Mr and Mrs Yousaf and their daughter Tanya - herself a mother-of-two - were surrounded and shot several times while praying at the cemetery.
The killings were allegedly triggered by a divorce between Mr Yousaf's son and a girl in the nearby village.
Two of the suspects, brothers Shiraz and Naveed Arif, were granted pre-arrest bail in Pakistan but failed to attend court and went on the run.
The family has criticised the Pakistani police and government, and the British authorities, for their lack of action in apprehending the men.
Relatives set up a campaign group on the social network site Facebook, called Justice for the Yousaf family.
They said they had to arrange their own security when they attended the funerals in Pakistan.