Considering the way Mad Men concluded its third season (with Betty Draper sitting on a train, headed west with another man), many fans of this AMC drama are wondering:

How much will we see of Don's home life on season four? The answer, apparently, is: a lot.

A new casting tidbit makes that much clear. Kiernan Shipka, who plays Don's daughter Sally, has been promoted to series regular.

"Last season was really hard for Sally, and next season is going to be even harder," the actress told TV Guide. "It's really going to be about Sally growing up and reacting to whether her parents get divorced or not."

The new season of Mad Men premieres on July 25.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.