The couple is auctioning off a night out with them for charity
Credit: Emma Heming Willis

After moving from the west coast to New York, Emma Heming Willis, 37, was searching for an organization she could “plant roots” with – and discovered Room to Grow, a charity that works to enrich the lives of babies born into poverty.

“As a mom, your mother instinct kicks in and it’s not just for your children, it expands outwards,” Emma – who has daughters Mabel, 4, and Evelyn, 23 months, with husband Bruce Willis – tells PEOPLE. “It’s a terrific charity. There’s so many layers to it and I’ve just really taken to it.”

She adds there was another connection that drew her to the organization.”My mother is a single mom so this charity just really spoke to me because it helps families, but they also really help single moms.”

Emma feels so passionate about the work Room to Grow is doing she has become their new ambassador as well as the honorary chair at their upcoming annual spring benefit on Thursday.

The benefit, which includes a dinner reception along with a live and silent auction, hopes to raise close to $500,000, says Emma.

“One of the live auction items is going to be a date night with my husband and I,” she says. “We’re going to take the winning bidder to see Sting and Peter Gabriel in concert.”

As for how hands-on her movie star husband is with the organization, the designer-model says, “He’s super involved.”

“It’s great and it just really helps the organization in a big way,” she shares.

Emma says Bruce’s daughter’s with ex-wife Demi MooreRumer, Scout and Tallulah – were also eager to lend a hand.

In fact, the family recently turned their vacation in Turks and Caicos into an opportunity to raise money for the charity.

“I wanted to set up a lemonade stand, which then turned into this ice pop stand, for the two younger Willis girls and then Rumer, Scout, Tallulah and my husband jumped in and were selling ice pops,” shares Emma.

She adds with a laugh: “My husband was eating the merchandise. I was like, ‘You’ve got to stop eating.’ But he donated so it was okay. We have a really supportive family and they’re always so willing to jump in whenever they can.”