When the Short family arrives at their vacation resort in the Yucatan, their accommodations aren't quite what they expected. Also, Heather is ridiculously overprotective of Sophia during the family activities; Jen and Greg discover that Matt and Colleen have been duping everyone; and John and Joan get separated from their tour group in the jungle.
When Colleen and Matt try to impress a potential birth mother, they have a hard time competing against another rich, swanky couple. Also, Jen's pregnancy takes a toll on Greg; Heather lets John take credit for her housekeeping while Joan recovers from knee surgery; and Tim arranges for Tyler to record a demo at a friend's studio.
While Joan is bedridden recovering from surgery, she persuades Sophia to spend time with her, which she quickly regrets. Also, Jen and Greg select a name for their new baby only to learn that Matt and Colleen chose the same one; Colleen and Matt invite the family over to get to know Morgan; and Heather has a new business idea.
When Colleen and Matt learn they may not be allowed into the delivery room for the birth of the baby they are planning to adopt, they try to convince Morgan to have the baby at home. Heather is thrilled when Samantha has a falling-out with a friend who was a bad influence. Jen thinks Greg bought her a beautiful present only to discover it wasn't for her. John encourages Tim to see a cardiologist.
After Tim has a heart attack, he becomes super clingy and annoys the entire family. Also, Greg and Jen make a pact to keep their baby's gender a secret; Sophia's new pet frog turns out to be a dangerous species; and Matt and Colleen receive news about their impending adoption.
After John befriends the janitor at Sophia's school, Mr. Sissel (Biff Wiff), John learns that Sophia and her friends believe a childish rumor about him. Also, Heather pushes Tim and Joan to go for walks together while recovering from their health issues; Matt and Colleen try to tame Dougie's (Fortune Feimster) bad habits; and Jen is desperate to not go into labor during Lark's birthday party.
Greg scrambles to find Lark when he loses her at the hospital while visiting Jen and the new baby. Also, Heather offers to help Sophia with her math homework but can't figure out the new teaching method; Matt enrolls his adopted son, Lucas (Vivaan Bisoi), in a father/son art class; and Colleen organizes a family photo shoot and glams Joan up for the occasion.
Heather and Tim get an emergency text from Samantha to pick her up in the middle of the night, and they try not to freak out so she'll still think they're the "cool" parents. Also, at the circus, Tim endures an embarrassing public situation; John accidentally walks in on Jen breastfeeding the baby; and Greg and Matt get competitive over their children's accomplishments.
When Tim gets a toupee, the family members try their best to hide their horrified reactions. Jen fights for face time with her boss when she returns to work after maternity leave. Joan decides to retire but gets cold feet. Greg and Matt build a playhouse for the kids.
Matt and Colleen treat Jen and Greg to a fancy dinner as a 'thank you' for writing a recommendation letter, and Jen and Greg are mortified when they realize they never wrote it. Sophia asks Tim and Heather to get her a pig. Clementine wants Tyler to stop going to his paediatrician for medical care now that he is an adult. John's parents decide to get a divorce.
Jen and Greg hire Edna-the cleaning lady who has worked for John and Joan for years-but Jen is horrified at her strange habits. Matt, Heather and Greg race to find the valuable souvenir pens John brought them when they were kids. Lucas is terrified of Joan. When Tim invites Matt over to watch a sporting event on television, it takes a weird turn.
When Matt helps Grandpa Mort efficiently book a family trip to the Bahamas, the family is super impressed, so Greg reserves a cabana at the pool to outdo Matt. Tim saves the life of a fellow hotel guest. Matt and Colleen take an excursion to a private island. John learns some astonishing news about his father.
When Tim and Heather realize that being grandparents is very far off in the future, they decide to have another baby. Joan gets frustrated when she keeps getting tasked with watching the grandkids. Jen and Greg decide to look for a new house. Matt gets a job offer in Germany, which is problematic for Colleen and Lucas.