During the 1960’s and 70’s, a number of new housing estates were established in the western part of St. Mary’s parish. Marian Park was completed in 1958 and Ballsgrove completed by 1966. The church and schools of St Mary’s parish could not cater for the increase in residents in the area. Land was acquired for the development of new parish buildings and in 1969 Marymount Girls’ School was opened.
A new housing estate was built in Rathmullen which was in the parish of Donore. However, the residents preferred to maintain their links with the adjacent parish of St. Mary’s. In the early 1970’s, a 2.5 acre site was acquired at Ballsgrove from Drogheda Corporation. On 28 October 1973, the church which was dedicated to the Holy Family was blessed and officially opened. The building cost £192,000 and was designed to seat approximately 850 people.
In 1979, on the recommendation of the priests of St Mary’s parish, initial plans were made for the setting up of a separate parish. On 14 February 1986, the Diocesan College of Consultors approved the suggestion and a Boundaries Commission was set up.
On the 27 August 1986, the Most Rev. Michael Smith issued the following decree:
‘A second new parish is to be erected on the western side of St Mary’s and will be called Holy Family parish. It will include the following areas: Ballsgrove, Rathmullen, St Finian’s Park, Donore Avenue, Donore Road, Cherrymount, Cherrybrook Drive, Hillbrook, Marian Court, Hill View, Highfield, Laurel Court, Grove Road, all houses opening on to Marley’s Lane, St Oliver’s Community College, Marian Park nos 1-66, 131-140 and 183-232. The remaining houses in Marian Park will remain in St Mary’s
Today the M1 motorway forms the boundary between St. Mary's Donore, and the Holy Family Parish.