Britney Spears's fake cousin, Alli Sims is set to testify for at least four hours on Aug. 29 at the office of Kevin Federline's lawyer, Mark Vincent Kaplan, LIFE & STYLE WEEEKLY reports.

The Kevin Federline & Britney Spears custody battle heats up

“She’ll have to repeat her testimony when the custody case goes to court, which could be six months away,� a source says

And it’s only the beginning, a Kevin insider reveals. The people closest to Britney Spears - friends, assistants, bodyguards and nannies who have seen her interact with the kids on a daily basis — are likely to be subpoenaed as well. “There’s a hit list,� says the Kev insider. “It includes a number of people who are in the know in Britney’s life, primarily people who have worked with her.�

Britney, 25, is devastated by the turn of events. “She’s very upset that Kevin wants custody,� the insider says. “She can’t understand how anyone could take her babies from her. She thinks she’s a good mom and feels like everybody’s out to get her.�