Jenna Dewan's Daughter Everly Loves Having 'More Responsibility' as Big Sister to Baby Rhiannon: 'Really Beautiful' (Exclusive)

Jenna Dewan's family just got a little bit bigger — and she's figuring out how to balance it all.

The Rookie star, 43, spoke with PEOPLE about her new partnership with Neostrata, opening up about how life has been since welcoming her baby daughter Rhiannon in June. Her newest little one joined big sister Everly, 11, whom Dewan shares with ex Channing Tatum, and big brother Callum, 4, whom she shares with fiancé Steve Kazee.

"I think I had the idea it was going to be so hard," Dewan tells PEOPLE of going from two kids to three. "I'm thinking, 'How in the world do you do three kids?' But I always tell people to leave room in your brain, in your mind, about it actually going better than you think, always in all areas of life, not just with parenting."

"And when Rhiannon was born, and we came home from the hospital, I was like, 'Here we go. This is going to be...How do we do a toddler, an 11-year-old and a baby?' And it just really was smooth. It was pretty smooth."

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Not only are Dewan and Kazee in love with their new little one, but Everly can't get enough of her baby sister.

"We take her around the house, wherever my other kids are, and she loves it," Dewan says of her younger daughter. "She gets all the attention and they play with her. Evy really likes to hold her."

"Her new thing is to put her in the little carrier that I always wear Rhiannon in, and she loves to bounce her and put her to sleep in the carrier," she continues. "She's getting into this more responsibility as a big sister. It's been a really beautiful flow that's happened."

As Dewan has entered her fourth trimester, the actress says she's been leaning on Neostrata's Triple Firming Neck Cream as she balances her work with her responsibilities as a mother.

"For me, being a new mother and also having two other kids, it is all about multitasking and being able to find products that do multiple things at once to help me fight the signs of aging and also just have the overall healthy, even, glowing skin as much as possible," Dewan explains.

The star has been prioritizing using Neostrata's neck cream, which she calls a "game changer," because she can use it all over her neck and on her chest.

"To have a product that also has peptides and all these incredible products in there that are going to multitask is everything for me," Dewan says. "Because I need a few products and that's it. I can't be doing this long, drawn-out routine."

As her daughter starts to enter her pre-teen years, Dewan says Everly's been getting more into makeup — which the actress loves.

"It was like overnight, I woke up and she's in my makeup drawer, loving to try on different kinds of lip glosses," Dewan shares. "And she likes a lot of cheek, she likes a lot of blush and a little bit of lip gloss and she plays around, and I think it's fun and it's creative."

"I used to love that as a kid, I was in my mom's makeup drawer. And she just thinks it's a fun expression of her own personality and what she likes to feel. She likes to change it up like, 'Today I'm going to dress like this and I'm going to try on this color lip gloss,' " Dewan says of Everly.

"We're in the preteen years. We love makeup. She is definitely similar to me," adds the proud mom.

Dewan, who has been appearing in The Rookie since season 3, has been able to take her baby daughter to set with her as they've been filming, which the actress says has been "amazing."

"I'm able to keep feeding her, I'm able to go back and forth between scenes and breastfeed. She comes in the hair and makeup trailer with me and gets to cuddle and hang out while I'm getting ready," Dewan shares.

"So I feel really grateful that I have the life and the job that she's able to come with me, which is why I'm able to go back to work sooner than a lot of people. Six, seven weeks is pretty soon, but she was with me a lot of the times."

Of course, it's all part of a balancing act, but Dewan says she's feeling a lot more confident with baby No. 3 than she did with her first baby.

She adds, "It's definitely a juggling act, but it's flowing for now."