Lynne and Shar's Friendship upset Britney Spears

Britney Spears's mom relationship with Kevin Federline's first ex, Shar Jackson, caused huge problems reports US Magazine

While Britney, 25, was at Promises Treatment Center following her dramatic head-shaving incident, Lynne was getting to know Shar

After meeting, Lynne and Shar "started talking all the time," a Jackson source tells Us. Spears was enraged. "She decided she had to cut out everyone who was using her, and that included her parents," says a source.

Jackson confirmed the friendship for Us, saying, Lynne is "a really nice lady... It was easy for us to get along once we met." She also thinks it's time for Lynne and Brit to "work it out. They are mother and daughter. They need to talk already."