PRIVATE PRACTICE - "Are You My Mother?" -- Cooper struggles with whether or not to punish Mason after he catches him stealing; Pete and Violet find it hard to split time with Lucas now that they're living apart; Addison makes changes in her home life to prepare for a potential new baby; Violet and Jake work with two women and a man involved in a polyamorous triad; meanwhile Amelia returns to the practice and realizes how badly she hurt Sheldon when she was abusing drugs, on "Private Practice," THURSDAY, JANUARY 5 (10:02-11:00 p.m., ET) on the ABC Television Network. (ABC/RICHARD FOREMAN) KATE WALSH