Kevin Federline's attorney says he wants to take another step in the custody battle with Britney Spears and depose the pop star.

"Britney Spears will have her deposition early (next) year," Mark Vincent Kaplan told People.com late Saturday outside a Beverly Hills restaurant. "We've got a lot to talk about."

Spears, 26, called in sick to a court-ordered deposition Dec. 12, although she was photographed that day driving with a friend.

Spears and Federline have been wrangling for months over custody of their sons, 2-year-old Sean Preston and 1-year-old Jayden James.

Federline, 29, has temporary custody of the children because Spears, who has limited visitation rights, has defied court orders. Spears and Federline were married in October 2004 and finalized their divorce in July.

Kaplan also said the children spent the holiday with their dad and their half-siblings (Federline has two children—Kori and Kaleb—with his ex, Shar Jackson).

"It was a good Christmas for all," Kaplan said. "They were great. Kevin had all of his kids and it was a big, wonderful family setting. He was really happy, and the kids were happy."