To offer a stronger ability in support of Catholic elementary education, McKees Rocks Catholic School was formed in 1979, through a merger of the former schools. The grades schools at other parishes closed their doors and students were welcomed to the new school which used the classrooms at Saint Francis de Sales. The former school at Saint Mary became the site for religious instruction and other parish functions.
After serving the people of Holy Trinity Parish for thirty-five years, Father Krysmalski died in January 1979. The bishop sent a new pastor, Father Robert Herrmann, by the end of the month. Father Joseph Farina died in February 1979, after serving Mother of Sorrows Parish for twenty-one years. A new pastor was not appointed until June that year when Bishop Leonard sent Father Matthew Cirilli to lead the parish.
The new decade continued to bring financial challenges across the diocese as the steel industry diminished drastically from its once prominent place in the region. With the loss of employment, people were forced to relocate, and the population dropped, including the membership in the parishes.
Despite the changes that the demographics predicted, both Saint Mark and Mother of Sorrows marked their 75th anniversaries in 1981. At the first, the church was cleaned and painted, and the stained glass repaired. At the second, as part of the festivities that unfolded over a year, beginning in 1980, Father Wilbur Farina, brother of the former pastor, burned the mortgage. A new residence for the pastor was purchased on Harlem Avenue, and work began on an activity building.
The parish communities of Saints Cyril & Methodius, Saint Francis de Sales, including Saint Maria Goretti Mission, Saint Mary, Help of Christians, Saint Vincent de Paul, and Mother of Sorrows joined together for the celebration of the sacrament of confirmation in May 1981. The number of candidates totaled 165.
Struck by lightning in 1982, a fire damaged the new church at Saint Malachy. During the repairs, worship was moved back to the former church, which had become the school gymnasium. In 1983, work began on a new rectory and administration building for the school. Father Oldenski received a new assignment, and the bishop sent Father Robert Staszewski as the new pastor of Saints Cyril and Methodius.