Maddie is distressed to learn her younger sister, Mia, is engaged to a guy she's only known a short while. Meanwhile, the siblings' parents are overjoyed with the news.
Mia and Casey go house hunting and she becomes concerned when he takes a liking to an old, run-down firehouse. Meanwhile, already retired Vicky sees her ordered life become unsettled as recently retired Joel has trouble keeping himself occupied.
Ben is a little put out when, after nine years of being left out of the Putneys' annual Christmas-card photo, new-to-the-family Casey is asked to sit in. So Ben and Maddie design their own holiday greeting card.
The course of true love hits a pothole when Casey and Mia have their first fight, but Casey comes up with a foolproof plan to help smooth over all disagreements. Meanwhile, Maddie inadvertently exposes a fault in her relationship with Ben, while Vicky and Joel share their unique take on resolving marital spats.
Ben tries to get Vicky to stop sending him silly e-mails, and Maddie has a plan to help. Meanwhile, Mia tries to convince Casey that being pregnant is no reason to curtail lovemaking.
Maddie boo-hoos the fact that her birthday falls on Halloween and overshadows her special day, so Mia and Casey offer to treat her to a party at their new home. Meanwhile, Ben forgets what Maddie wants for a gift, and Joel offers him some advice on how he always handled such a situation; and Mia finds a mysterious videotape among Ben's things and wonders whether she should sneak a peek at it.
When the guys take a road trip to Vermont to get Casey's stuff out of storage, Ben sees the journey as a chance to get to know Casey better, while Joel envisions it as an opportunity to become a father-in-law gone wild. Back at home, the women throw a baby shower for Mia and invite Casey's quirky and demanding mother, who causes a ruckus with Vicky when both future grannies want to be known as Nana.
Mia and Casey are excited when Maddie gets them a meeting with one of the top wedding planners in the city -- the charming but very expensive Lorraine Ashley. But the too-good-to-be-true arrangement turns awkward when it looks like Lorraine is trying to upstage the couple's pending nuptials. Meanwhile, Ben realizes that he has been with Maddie for so long that his "flirting muscle" has gone soft.
Vicky's oven breaks down just before Thanksgiving, which is actually a blessing since now the rest of the family won't have to gobble down one of her outlandish, unpalatable turkey-based fiascoes. When the celebration is moved to Maddie and Ben's, Mia discovers her late grandmother's ring that was supposedly stolen, and now Maddie has some serious explaining to do.
When Maddie discovers Mia is using her pregnancy as an excuse to opt out of the dreaded family Christmas at their parents' lake house, Maddie fabricates a yarn of her own to get out of the trip.
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 prove to Casey that the U.S. Postal Service is a first-class operation.
After the pediatrician tells Mia and Casey that their newly adopted cat should not be around the baby, the news triggers a competition between Mia's parents and Maddie and Ben, who believe whoever takes in the feline will also be named the baby's guardian.
Ben and Joel tell Casey, who is marking his first Valentine's Day with Mia, that it sets a bad precedent to spend too much on a gift, but he ignores their advice, which leads the other two to break the bank to impress their ladies.
Casey heads out for a job interview and borrows a leather jacket without telling anyone, unaware that the coat has a history of bringing bad luck to its wearer. Each family member recalls a calamitous experience while sporting the coat. Among the tales of woe: Ben once accidentally interfered with the New York Yankee's Nick Swisher as the outfielder was trying to snag a fly ball.
Ben hopes to get his name inscribed on a shamrock at his favorite bar, but it looks like he will strike out in his efforts when he learns the establishment's owner is New York Yankee Nick Swisher, with whom Ben has a bad history. Meanwhile, Mia and Maddie use a secret language to convey their apprehension about attending a charity event with Vicky.
Casey finds out that his ex-girlfriend wants to pick up the couch she lent him before their breakup - the same couch 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. Meanwhile, Maddie updates Vicky and Joel's wills, but finds they won't take her professional efforts seriously.
Maddie's joy at being named partner at her law firm is short-lived when she is laid off, and she tells everyone she quit to take a better job. Meanwhile, Mia and Casey suspect there is a secret negative message in a children's book that has been passed down through generations.
On the eve of Mia and Casey's engagement party, the sisters begin to suspect there is something fishy about each other's tales about how they met their men. Meanwhile, since the celebration is at Vicky and Joel's country club, Joel thinks it could afford him the opportunity to save money in his campaign to be elected club treasurer.
To prep for their wedding reception, Casey and Mia take a dance class, where he, a very accomplished dancer, discovers that she has two left feet. Meanwhile, Ben seeks relationship advice from talk-show host Larry King who is staying at Ben's hotel.
When a very pregnant Mia realizes her condition will prevent her from participating in many of the wedding-day festivities, she and Casey decide to postpone the ceremony until after the baby is born, and then set out to recoup their deposits. Meanwhile, Ben decides to have some fun with Joel when he discovers the father of the bride is unable to stop shedding tears while preparing his wedding-day toast to his little girl.
Mia covets a top-of-the-line stroller for the baby, so granddad-to-be Joel does his wheeling-and-dealing best to score a hefty discount on one. Meanwhile, jobless Maddie ponders whether she still has the drive to be an attorney.
Mia goes into labor, only to decide that she and Casey should bring their baby into the world as a married couple. So Casey and Ben zip over to City Hall for a license, while Maddie scrambles to find an authorized official to perform the ceremony. Meanwhile, the grandparents-to-be scour the gift shop for the traditional something old, something new, something borrowed and something blue.
