Evan Ross and wife Ashlee Simpson Ross welcomed son Ziggy Blu in October
Ashlee Simpson Ross and Evan Ross Family Photos
Evan Ross, Ashlee Simpson Ross and daughter
| Credit: Ashlee Simpson Ross/Instagram

Ashlee Simpson Ross and Evan Ross' daughter wasn't initially into the idea of having a baby brother.

On Wednesday's episode of SiriusXM's The Jess Cagle Show, Ross, 32, opened up about how the couple's 5-year-old daughter Jagger Snow has handled becoming a big sister to their son Ziggy Blu, who was born in October. 

"Well, she loves the baby but when she found out that it was a boy, at first, she was super, super mad," Ross said. "She was furious." 

"We did a gender reveal with the whole family on Zoom and I could see her like, on my side and it was like, she broke down," he added, playfully recreating her reaction. "[She] was like, so upset." 

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Ashlee simpson and family
Ashlee Simpson and family
| Credit: Erik Melvin
Ashlee Simpson newborn
Ashlee Simpspson and Ziggy Blu
| Credit: Ashlee Simpson/Instagram

Fortunately, everything changed after Jagger met her little brother. "Now, she's a great big sister. She kisses him probably every five seconds," Ross says of his daughter.

Jagger has also gotten help from 12-year-old brother Bronx Mowgli, whom Simpson Ross shares with ex-husband Pete Wentz

"Bronx, their older brother, is the most chill guy. He's so well-grounded and takes care of both of them so well," he explained. "Jagger's become this great big sister. He helps her with it too so she doesn't feel like she's having to share the attention." 

RELATED VIDEO: Ashlee Simpson Shares First Photo of Children Bronx and Jagger with Their Newborn Sibling Ziggy

Since welcoming their son, Ross and his wife have posted several cute photos of their happy family on social media.

The "Pieces of Me" singer, 36, shared the first sibling photo of her three kids in November, just days after the newborn's arrival.

For Bronx's birthday later in November, the proud mom debuted the first photo of their new family of five for the occasion. "Happy Birthday Bronx!!" Simpson Ross wrote in the affectionate post. "You are the coolest, kindest, deep, soulful kid (almost teen) and I am so lucky to be your mom! We love you so much! Happy twelfth"

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Since then, Ziggy has also gotten a chance to meet some other very important family members, including aunt Jessica Simpson.

Earlier this month, Simpson shared an adorable snapshot of her youngest child, daughter Birdie Mae, 22 months, curling up beside her young cousin. 

"#ZIGGYBLU + #BIRDIEMAE," Jessica, 40, captioned the black-and-white photo of the two youngsters peering into the camera.