Complex sentence: Since 2001 it has grown to Regerchor-International in a collaboration with the organist Ignace Michiels of the St. Salvator's Cathedral of Bruges, performing an annual concert both in Germany and Belgium of mostly sacred choral music for choir and organ.
Split into simpler sentences: Since 2001 it has grown to Regerchor-International in a collaboration with the organist Ignace Michiels of the St. Salvator's Cathedral of Bruges. The choir performes an annual concert both in Germany and Belgium of mostly sacred choral music for choir and organ.