Complex sentence: A week later, it was announced that Jonathan Donais of Shadows Fall would become the band's touring lead guitarist, and on August 13th, it was announced that Donais had become an official member of the band.
Split into simpler sentences: A week later, it was announced that Jonathan Donais of Shadows Fall would become the band's touring lead guitarist. On August 13th, it was announced Jonathan became an official member of the band.