Sibling rivalry already? At the Jan. 23 Sundance Film Festival premiere of A.C.O.D., Jessica Alba told Us Weekly that being a mom to two growing girls -- Honor, 4, and baby Haven, 17 months -- definitely has its fun moments, especially now that Honor is getting comfortable with her big-sister role. 

"She loves it, she's super into the fact that she can do, like, so much more than what the baby can do," the Sin City actress laughed. "She's like, bonus!" According to Alba, her spunky older daughter enjoys showing off everything from how she can "eat cupcakes and like, swing on a swing all by herself and ride a bicycle -- with training wheels, mind you!"

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"And she can play with Polly [Pocket] because she doesn't put them in her mouth, because the baby puts the Pollies in her mouth," she adds. "You know, important stuff."

Alba, 31, and husband Cash Warren, 34, welcomed their second baby Haven on Aug. 13, 2011, and almost immediately fell head over heels in love with their family's newest addition.

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"I'm not going to pretend like I wasn't concerned about bringing another little one into the world. I mean, Honor was our everything!" she wrote on her iVillage blog shortly after Haven's birth. "How would it be possible for us to love anyone, in a million years, as much as we love her?!? Frankly, I didn't think I had the capacity. But literally, overnight, everything changed as little Miss Haven shed her bright light on us and all of our hearts burst open even further."

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But Honor, who is often snapped wearing a number of fashion-forward ensembles with mom, is definitely making sure that her parents aren't just giving baby Haven all their attention, Alba has said.

"She's very independent, very opinionated and loves dress up so much," Alba told Rachael Ray of her little fashionista-in-training during an interview last January. "Like, every day, she's in full drag! She wears a wig every day. She has a lot of wigs and she has a lot of plastic heels. It's totally insane, but it makes her happy."

This article originally appeared on Jessica Alba's Daughter Honor Loves Showing Off in Front of Baby Sister Haven