After becoming friends in the end, Brad Whittaker (Will Ferrell) and Dusty Mayron (Mark Wahlberg) make a system of co-fathers with their children, Megan and Dylan, to turn to each of their fathers’ homes. Dusty remarried himself again, this time with a writer named Karen (Alexandra Ambrosio) and is a stepfather for Karen’s daughter Adrianna. Brad and his wife, Sara (Linda Cardellini), together with Dusty and Karen, take part in a show that features Megan. As part of the show, in front of the whole audience, Megan complains that he has to go from house to house and that he does not like it. After the show, when you get home, Brad and Dusty decide not to spend the separate Christmas and make a good one with the whole extended family. As soon as Dusty tells the children, the phone starts to ring. Dylan responds and announces that the phone is “Grandpa Kurt” (Mel Gibson), the dying father and former astronaut of Dusty! Kurt tells Dusty that he is coming to spend Christmas with him and that he has to take him to the airport the following morning. Brad then tells Dusty that his parents are coming to spend the holidays together. At the airport the next day, Dusty tells Brad that his father will make fun of them because he will not understand their system. When Kurt arrives, he confuses Brad with a driver. When Dusty explains that Brad is the stepfather’s father, Kurt is totally unhappy.