"We are overjoyed to bring the first grandchild into both families this summer," Allen says. "We don't know boy or girl, but we are pretty sure our baby already has a palate for Indian food and Pinkberry."
Allen, 34, wed Weyman, a model, in Italy in 2006, two days before she began her role as Julia Mallory on Courteney Cox's Dirt.
"My whole marriage has been this ride," Allen told PEOPLE in 2007. "My husband is so supportive."