A former party girl marries a much older man knowing that he has "baggage" (two ex-wives and three children between them), and she soon realizes the baggage is going to bring new challenges every day.
Kate has to watch Bert while both Jackie and Pete are out for the evening, and she can't get Bert to surrender and go to sleep. When he is over-tired in the morning, a frustrated Kate gives him coffee. Bert is energetic at soccer practice that day, but crashes hard later. Meanwhile, Diane uses a little psychological torture to get Warren and Hillary to confess to an accident they had in the house.
When Hillary starts sneaking around on the weekends, Pete overreacts and makes matters worse. Kate tries to take over from Pete and Diane, but she finds that her own parental style needs work. Jackie tries to finagle a jewelry deal with the parent of one of Bert's friends.
When Meg needs Kate's help getting through a breakup, Kate finds herself torn between her obligations as a friend and her responsibilities as a wife and step-mom. Kate struggles to be a good friend to Meg, but when Meg's breakup drama gets to be too much, it leads to a falling out between them. Meanwhile, Warren figures out where his true talents lie when Jackie enlists his help with Bert's Lego project.
Finding it more and more difficult to spend time alone and away from Diane’s constant demands, Kate and Pete sneak away for a romantic tryst at the school fundraiser. But when they get trapped, truths come out and Kate reveals she wants to be at the top of Pete’s priority list and for him to stand up to Diane. Meanwhile, Warren and Hillary help Jackie with her online dating profile.
When Jackie’s homemade costume nearly ruins Bert’s Halloween, Kate steps in with the costume he wanted, and Bert’s so overjoyed that he asks Kate to take him trick-or-treating. This leads to a fallout between Jackie and Kate, which gets worse when Bert goes missing. Pete tries to get a neighborhood teen to admit he egged Pete’s house last Halloween. Diane steps in to intervene and Warren and Hillary get involved.
When Kate and Pete host a party, Jackie crashes and hooks up with Pete’s co-worker Sad Steve, much to Pete’s discomfort. However, when Sad Steve decides to pursue a relationship with Jackie, both Kate and Pete jump on the bandwagon to give young love a boost. Meanwhile, Hillary helps Warren and Bert put together a Gum Show live stream, and Diane faces off with Meg after she posts an unflattering picture of her on Instagram.
When the Harrison household is infected with lice, Diane tries to take charge leaving Kate feeling bulldozed. Jackie and Kate work together to try to prove a point to Diane, but their plan back fires and the lice problem worsens. Meanwhile, Pete plays mediator between Warren and Bert, who are fighting over custody of a teddy bear.
When Kate tries to play matchmaker with Diane and another parent on a field trip, she soon learns that Diane is more challenging to set up than she originally thought. Meanwhile, Jackie decides to nurse Pete back to health and Hillary helps Bert get on his teacher's good side.
Pete, Kate, Diane and Jackie wake up Christmas morning hung-over and the house in complete disaster. They try to piece together the events of last night’s Christmas Eve festivities while also trying to save Christmas for the kids.
When Kate attempts to break Pete's birthday curse and help him have a fun birthday, the curse proves to be more powerful than she anticipates. Meanwhile, Diane and Jackie shop together for Pete's birthday gift and the kids are at home with lobsters that refuse to be a main course.
When Hillary and Warren misbehave on Kate’s watch, Kate turns to Diane for help in disciplining them, and Pete and Jackie try to set a good example by taking Bert on a nice outing together, but it proves to be harder than they anticipated.
Pete's solution to losing Bert's tooth causes issues with Jackie; Kate gives Warren advice; Diane embarrasses Hillary when she helps her throw a sleepover.
Kate and Jackie butt heads when they try to work together on Jackie's latest business venture; Pete takes Warren and Bert to karate lessons.
When Bert successfully reads a hundred books, Pete and Kate have to throw him the birthday party of his dreams - complete with a fire eater on stilts, professional dancers and a special visitor. Kate uses the party planning as an excuse to get in with the soccer moms that shun her at all the games, and Diane refuses to admit fault while doing some creative driving with Pete. Meanwhile, Warren starts a bromance with the guy Hillary has her eye on.
When Kate finds Pete’s old wedding videos with Diane and Jackie, she realizes she robbed herself of that special memory by eloping and is now determined to have a redo and plans her dream wedding. Meanwhile, Diane decides to take her relationship with Russ Bradley Morrison public and Jackie struggles to tell Bert she’s dating Sad Steve.
Wedding planning continues as Kate will not be fazed by all the stress and chaos around her, which is only amplified by the arrival of her mother and Pete's parents. However, things come to a screeching halt when the family gets some bad news.
When Pete swaps out his chili for Kate’s at the school frontier fundraiser, Diane confronts him and he concocts a story about how he and Kate are going to couples counseling. Meanwhile, Meg relaxes at the Harrison’s house and becomes an object of fascination for Warren and Hillary.
After Kate saves Diane from choking, she takes over the PTA and finds it harder to navigate than she thought. When faced with blackmail, she turns to Diane to make sure “it’s handled.” Meanwhile, Pete and Jackie confront their former neighbors after they forbid their son to go to the school dance with Hillary, and Warren tries to get Vanessa Hudgens to be his date.
Concerned about Warren’s social life, Kate encourages him to make new friends and get involved in clubs or sports, however, it backfires and now she might have made things worse for him. Elsewhere, Hillary struggles with her art assignment and looks to Jackie for some creative guidance, and Pete teaches Bert the value of money.
Kate begrudgingly agrees to accompany Jackie to her high school reunion, not fully realizing all that it entails. Pete and Diane take Hillary and Warren to visit a college campus.
Kate is overjoyed when Diane and Jackie offer to let her have the kids on her first Mother's Day, however, when Kate discovers their hidden agenda, she is determined to get revenge. Meanwhile, Pete slowly buckles under the pressures at work.
