Kamaljeet Singh, Jaswinder Kaur (19) and Balwinder Kaur (16) were found dead in a car in Rarha village near here on January 31.
Police today arrested Singh's daughter Ramandeep Kaur for her alleged involvement in the murder of the trio.
During the preliminary investigations, it was found that both the girls were strangled to death and the man was brutally murdered, police said adding that deceased Singh was a person of "immoral character".
Singh's daughter Ramandeep and her friend Gurpreet Singh are alleged to have involved in the murders, police said.
Raids are being conducted to nab Gurpreet.