Complex sentence: For a while, Will is known as Will Roberts-Horton, and then, during a bad patch in Lucas's relationship with mother, Lucas drops "Roberts" from their names, and Will becomes Will Horton.
Split into simpler sentences: For a while, Will is known as Will Roberts-Horton. During a bad patch in Lucas's relationship with mother, Lucas drops "Roberts" from their names, and Will becomes Will Horton.