Ashlee Simpson and Evan Ross Are 'Leaving the Door Open' for Baby No. 4: 'Never Say Never' (Exclusive)

The couple is already parents to son Ziggy and daughter Jagger, while Simpson is mom to son Bronx with ex Pete Wentz

<p>Jon Kopaloff/Getty </p> Evan Ross and Ashlee Simpson at the Race to Erase MS 30th Anniversary Gala

Jon Kopaloff/Getty

Evan Ross and Ashlee Simpson at the Race to Erase MS 30th Anniversary Gala

Ashlee Simpson Ross and Evan Ross aren't ruling out having another baby.

The couple attended the 5th Jam for Janie Grammy Awards Viewing Party in Hollywood on Sunday and chatted with PEOPLE about whether or not they would consider growing their family.

The couple is already parents to son Ziggy Blu, 3, and daughter Jagger Snow, 7. Simpson Ross also shares son Bronx Mowgli, 15, with ex-husband Pete Wentz.

"We'll see, but I think so," Ross first responded when asked if the couple was done with having kids. "You never know."

"He's open. I'm more like, 'Eh, I'm about to turn 40,' " Simpson Ross joked. "But hey, never say never! I feel like once you get a kid in kindergarten, you're like, 'Am I done?' We'll always leave the door open."

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Related: Ashlee Simpson Shares Photos from Family Ski Trip — Including Impressive Snowboarding Video of Son Bronx

In December, the singer shared a few photos to her Instagram Story of her family's ski trip, which included an outing at an ice skating rink.

"Bronx and I trying to remember how to ice skate is always a good one," she wrote across the photo. "We eventually got."

Another sweet snap showed Simpson Ross's younger son Ziggy using a skate helper to learn how to ice skate. Bronx was pictured behind Ziggy, helping him push the plastic helper across the ice. "Well I don't know where we got to lol," Simpson wrote. "But this was everything!"

In November, Simpson Ross celebrated Bronx's 15th birthday, sharing a photo of the mother-son duo in honor of his big day.

Simpson Ross posed for a selfie with her son, who looked up from his phone and popcorn to take a picture with his mom, while in a movie theater.

"Happy birthday BRONX," the mom of three wrote across her photo. "Thank you for making me a mom! I can't believe your [sic] 15."

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