Mia invites her sister Maddie and her boyfriend Ben to meet Casey her new boyfriend. But Maddie quickly realizes that Casey is not just another boyfriend of Mia when they announce that they're engaged. Maddie is very surprise by the news and gets a little jealous that her little sister is marrying before her. She tries to be supportive and let her parents Vicky and Joel be the critical ones. But when Mia tell the news to her parents, her parent are very happy about it, much to Mia's delight and Maddie's surprise.

Everyone in the family hates the Christmas photo card that Joel obsesses over every year. But when Ben is left out of the card, he is really hurt when Joel invites Casey instead, so he and Maddie devise a revenge Christmas card. Meanwhile, Mia and Casey realize it is very hard for them to say "no", so they ask Maddie and Ben to do the hard work with their future baby.

Everyone in the family hates the Christmas photo card that Joel obsesses over every year. But when Ben is left out of the card, he is really hurt when Joel invites Casey instead, so he and Maddie devise a revenge Christmas card. Meanwhile, Mia and Casey realize it is very hard for them to say "no", so they ask Maddie and Ben to do the hard work with their future baby.

When Casey and Mia have their first fight as an engaged couple, Casey implements his plan that stops all arguments cold. In an effort to help, Maddie decides to show them how arguing can actually be healthy for a relationship, but ends up exposing a fault in her own nine-year relationship with Ben. Meanwhile, the longtime married Vicky and Joel quietly resolve their arguments by simply hiding each other's things.

Maddie plans to trick Vicky into choosing not to send frivolous emails to Ben; Mia tries to convince Casey that their romantic activities will not harm their unborn baby.

It's Halloween, which is also the date of Maddie's birthday. Because Maddie feels like she can never have a real birthday - since the holiday always steals the spotlight - Mia and Casey offer to give her a Halloween-free party at their new home, the renovated firehouse. Ben, however, wasn't listening when Maddie told him what she wanted for a gift, so Joel tells him about what he does whenever he messes up.

Ben and Joel go on road trip to Vermont with Casey in order to help him move his stuff out of storage, and while Ben wants to use this chance to bond with Casey, Joel has other things on his mind. Mia, Maddie and Vicky organize a baby shower which goes out of control when Casey's mother butts heads with Vicky.

Casey and Mia receive a big surprise when Maddie arranges a meeting with one of the top notch wedding planners in the city - Lorraine Ashley. However, their luck soon changes when the woman tries to upstage their event. Meanwhile, Ben comes to a realization that his flirting skills have gone downhill during his relationship with Maddie.

The entire family is relieved when Vicky's oven breaks down and she can't make one of her crazy Thanksgiving meals. Meanwhile, Mia accidentally finds her late grandmother's ring, which was presumably stolen, in Maddie's closet.

Mia and Maddie know their parents will give them an avalanche of guilt if they don't uphold the Putney family Christmas tradition of spending the holiday together at their lake house. When Maddie finds out Mia and Casey are using their pregnancy as an excuse, she tells Vicky and Joel her own tall tale to keep from having to go.

When Mia accuses Ben of ripping her favorite pair of jeans, she drags him to the store, where he has to break the tough news to Mia it's time for pregnancy pants. Meanwhile Joel decides to get himself into shape after he finds out he's ranked last in Vicky and her girlfriends' fantasy husband draft website, and Maddie goes to extreme lengths to impress Casey with her high regard for the U.S. Postal Service.

After parents-to-be Mia and Casey adopt a cat, the pediatrician tells them they shouldn't have a stray animal around the baby. Maddie and Ben enter into a spirited competition with Vicky and Joel, all under the impression that if one of them takes in Mr. Meow-gi, then Mia and Casey will name that couple as the baby's guardian.

Casey refuses to listen to Ben and Joel when they suggest he shouldn't buy an expensive gift for Mia for Valentine's Day because she might expect even better gifts in the future, so Ben and Joel both start competing with Casey by getting even bigger gifts to their loved ones.

The job interview-bound Casey, unaware that bad luck always follows the wearer of a particular leather jacket, borrows it without telling anyone. Everyone recalls their own bad experience while wearing the jacket, including Ben, who accidentally dropped a blanket on New York Yankee outfielder Nick Swisher when he was trying to catch a fly ball.

More than anything, Ben wants his name on a shamrock posted on the wall of his favorite bar. But his dream may be dashed when he learns that the bar's new owner is New York Yankee outfielder Nick Swisher.

Casey finds out that his ex-girlfriend wants to pick up the couch that she lent him before their breakup - the same couch that Mia and Casey are currently using. Since the Putney girls are known to be the jealous type, Ben assures Casey that he'll come up with the perfect plan to help him get rid of it without Mia knowing the real reason.

Maddie is ecstatic when she's told that she has made partner at her law firm. But just as soon as she tells everyone about her promotion, she gets laid off and, to save face, tells everyone she quit because she got a better job.

On the eve of Mia and Casey's engagement party, Maddie gets a feeling that the oh so romantic and charming story Mia has been regaling everyone with about how she and Casey met isn't true; and Mia starts to doubt her sister's story that she and Ben met while building houses for the poor.

Casey and Mia take a dancing class for the wedding, where Casey comes upon the conclusion that Mia is a really bad dancer and decides to pretend he is an even lousier dancer to make Mia feel better. Ben asks Larry King for advice on how to handle a fight he had with Maddie over Joel and Vicky.

When Mia realizes that she won't be able to partake in her wedding party because of her pregnancy, Mia and Casey decide to postpone their wedding until after the baby is born, but the problem arises when the bridal shop manager refuses to refund the money.

Joel works his bargaining skills and goes to extremes to get Mia the high-end baby stroller of her dreams. Meanwhile, an unemployed Maddie wonders if she's losing the passion it takes to be a lawyer.

Mia and Casey realize that they want to be married before their baby is born, so the entire family rushes to make things happen: Ben and Casey rush to get a marriage license, Maddie has to find a priest, and Vicky and Joel have to find the appropriate items to complete the ceremony.