"I'm really excited honestly for this Christmas because all of us crazy Pantaleonis are getting together," she told PEOPLE at the UNICEF Snowflake Ball Tuesday. (Leoni's grandmother, Helenka Adamowska, founded the U.S. Fund for UNICEF.) "All together there's something like 40 of us and there's a lot of singing."
"I have a lot of musical cousins," she says. "David will not be singing. We just encourage David to clap along."
Leoni and Duchovny are back on track after separating for several months in 2008 while Duchovny completed rehab for sex addiction, and on Tuesday, she praised her hubby for his theater debut in the off-Broadway show The Break of Noon.
"I think getting over opening night, his first opening night of his life, was a huge milestone," says Leoni, who is currently filming Tower Heist in New York with Ben Stiller and Eddie Murphy. "And he did it with such grace and flying colors … I'm very proud of him."