Credit: Jean Baptiste Lacroix/; Bryan Bedder/Getty Images

Ali Lohan is raising eyebrows again -- because of her eyebrows.

The 16-year-old aspiring model joined older sis Lindsay at Millions of Milkshakes in L.A. Monday, serving up goodies to customers.

She had noticeably darker eyebrows.

Ali is currently at center of an increasingly ugly family feud involving Lindsay, 23, and their estranged father Michael.

On Apr. 23, Michael -- who claims Lindsay is abusing drugs again -- staged an intervention, barging into her L.A. home with the Los Angeles County Sheriff's Department because he felt Lindsay was a bad influence on Ali. (After inspecting the house and interviewing both girls, officers determined Ali was not in any danger.)

Dina Lohan tells Lindsay and Ali may seek a restraining order against Michael. But his lawyer tells Us he simply is trying to "save and protect" his daughters and may pursue "legal action" to try and get Lindsay's life under control.