Margaret is the actress Barney hired to portray his wife.

In The Stinsons, the gang assumes that Barney is in a relationship and follow him, when he leaves the bar, to a house in Staten Island. There they meet his mother, Loretta, and his wife Betty and son Tyler.

When Loretta is out of ear shot, Barney explains that a few years ago, his mother was seriously ill and it looked like she was going to die, Barney hired Margaret to play his fiancée, to make his mother happy. To make Loretta even more happy, Margaret blurted out that she was pregnant. So when Loretta got better, Barney had to keep Margaret around, and hire a child actor named Grant to play his fake son Tyler.

While Ted and Margaret are alone in the kitchen, they bond while discussing a play Margaret was in. Later, everyone walks in on them kissing in the kitchen. At first Barney tries to "confront" "Betty" and Ted, but later tells his mother the truth.