Cooper caught Mason stealing and fretted about how to handle disciplining him. Meanwhile, Pete and Violet had trouble splitting time with Lucas now that they're living separately.
Addison came close to adopting a baby, and also ended her relationship with Sam. Violet and Jake worked with a polyamorous threesome.
Moreover, Amelia returned to work and realized how badly she hurt Sheldon when she was abusing drugs. Sheldon had trouble forgiving Amelia, while Charlotte stayed close to support her.