Tsen particularly emphasized on the importance of adoring the Blessed Sacrament and intercessory prayers, and had the Blessed Sacrament Chapel built for adoration and intercession. He also showed great interest in the healing and deliverance ministry, and sent some parishioners to Kota Kinabalu to attend seminars. He organized a number of Masses for the healing of the sick in the Parish. He started several Bible Sharing and Study groups. He renovated the old Boys’ School for Sunday School use and other spiritual activities. It is now named as the Father Mulder's Catechetical  Centre. Tsen went on a long leave in September 2004 and in his absence, Rev. Fr. Saimon William was appointed acting parish priest until the arrival of Rev. Fr. Simon Kontou in December 2004. After Rev. Fr. Paul Lo's ordination, he was assigned by the then-Bishop John Lee to Sandakan as the second assistant priest. For the first time in many years Sandakan was blessed with three priests. However, this number was reduced to two again when Fr. Saimon was transferred to Lahad Datu in October 2006. During his tenure in Sandakan, Fr. Simon had done a lot to beautify the church compound. He initiated the recycling programme and asked the parishioners to donate recyclable items to the church to collect funds for his beautification projects. With the funds, he had a waterfall constructed near the Grotto. Many flowers and trees were planted, and grounds of the church were beautifully landscaped. He could have been a botanist, for he did much of the planting himself personally! The prospect of Sandakan being erected to a diocese on the East Coast began circulating at the end of 2005. This probability was more or less confirmed with the visit by the Apostolic Delegate in Malaysia, Archbishop Salvatore Pennachio, to the three main parishes on the East Coast. On 16 July 2007, it was officially announced that Pope Benedict XVI had appointed Rev. Fr. Julius Dusin Gitom as the first bishop of the Diocese of Sandakan, a suffragan of the Metropolitan See of Kuching, thus becoming the third diocese in Sabah after Kota Kinabalu and Keningau. The new diocese covers the entire East Coast of Sabah which comprises the parishes of St. Martin in Telupid, St. Dominic in Lahad Datu, Holy Trinity in Tawau, and St. Mary in Sandakan.