Complex sentence: In the first months of 2008 there was great speculation that Brissia was going to leave the group as she missed a couple of concert dates and did not participate in the U.S. tour that La Nueva Banda was doing as the opening act for RBD.
Split into simpler sentences: In the first months of 2008 there was great speculation that Brissia was going to leave the group. She missed a couple of concert dates and did not participate in the U.S. tour in which La Nueva Banda was the opening act for RBD.