In 1966, Rev. Władysław Karwacki, appointed a cooperating vicar in Bolesławiec, was instructed to organize an independent vicariate, and from then on the Brzeźnik parish had its own pastor. The following localities from the Bolesławiec parish were incorporated into this parish: Bolesławiec, Dobra and Mierzwin. The parish was officially erected by a document dated 21 March 1969. The seat of the parish was moved from Brzeźnik to Bolesławiec. From then on, the parish was called: “Roman Catholic Brzeźnik Parish with its seat in Bolesławice.” The above decree took effect on 1 April 1969.
In 1969, Rev. Edward Bober, administrator of the parish in Marciszów, was appointed a cooperating vicar in the Bolesławiec parish, tasked with rebuilding the former Protestant church, which was handed over for use by the Bolesławiec parish that same year. An independent vicariate was established on 1 January 1970. Rev. Edward Bober became rector of the restored former Protestant church. From that time, approximately 60 streets were incorporated into the new parish, and the boundary between the mother parish and the newly established parish ran along Kościuszki, Tamka, Dzier­żyńskiego, Rynek, Kutuzowa, Komuny Paryskiej and Armii Ludowej streets. From then on, approximately 20,000 residents remained in the mother parish. In 1972, the newly established parish dedicated to Our Lady of Perpetual Help received several more streets from the mother parish. From then on, the parish boundary ran along Kościuszki, Tamki, Dzierżyńskiego, through half of Rynek, and along Kutuzowa, Kubika, K. Miarki and Jeleniogórska streets. The last two streets belong on one side to the parish of Our Lady of Perpetual Help. Since 1970, the following localities have also belonged to the newly established parish: Bożejowice, Łąka, Otok and Rakowice.
As time passed, the boundaries of the mother Bolesławiec parish dedicated to the Assumption of the Blessed Virgin Mary contracted. Today, within the boundaries where the mother parish initially operated, in 1945, a further nine parishes function.