Just when you thought it was safe -- with Lindsay Lohan still sort of in rehab -- there's another Lohan lurking.

Ali Lohan, Lindsay's 13-year-old sister, has already made brief cameos in all of LiLo's films, including "Life-Size" on TV and "Freaky Friday" in theaters. Although none of that shows up on IMDb.

But Ali -- or as she will no doubt be known,  "ALo" -- made her official acting debut in LiLo's music video "Confessions of a Broken Heart (Daughter to Father)" playing a younger Lindsay. So we know she's probably familiar with Lindsay's acting-out Daddy issues.

She's reportedly in negotiations with Disney Channel programming and made her singing debut in 2006 with the Christmas album "Lohan Holiday." Wonder if they play that during Lohan family therapy sessions?

ALo's reportedly a Ford model and appeared on the cover of CosmoGirl, albiet with Lindsay. But she was all on her own in Sweet 16 Magazine's "Sweetest Stars 16 and Under" in the February/March 2007 edition.

And she's already got her big sister worried. Lindsay recently told Britain's "Top of the Pops": "My little sister Aliana's opinions are the most important to me. She says, 'I want to look like you, you're so pretty!' But she is very beautiful and so she is trouble in the making!  I'm like her second mother and I am very protective of her."

ALo has even been on TMZ already! In August, the site debunked a news report (click HERE to read it) about the little Lohan sneaking out of the house to see her 16-year-old boyfriend, who then crashed his car. Just like her poor sister, people are already making up stupid stuff up about her. The report was untrue, Lindsay's publicist told TMZ.

Most telling of all, on ALo's website (click HERE) she says she "aspires to become an actress like Lindsay."

I say, why limit yourself? Why not become an actress like Charlize Theron or Cate Blanchett? Think BIGGER, girl!

Photo credits: Lindsay and Ali do a bikini sister act in Malibu on LiLo's birthday. Later, all three Lohan ladies pose together, and look where ALo's hand is. I smell trouble!
WireImage