Erin and Ben Napier welcomed their second baby, daughter Mae Napier, on May 28

Erin and Ben Napier, This Is Us
Credit: Erin Napier/Instagram. Inset: Gary Gershoff/Getty

Erin and Ben Napier's daughter's name was revealed on live TV several months ago — but not on an episode of Home Town!

On Monday, Erin, who welcomed her second baby, daughter Mae Napier, with husband Ben on May 28, revealed that her newborn's name was subtly snuck into an episode of This Is Us.

Thanks to the couple's friend, Chris Sullivan, who stars as Toby Damon on the NBC show, baby Mae's first and middle names were hinted at during a February episode of the show. Mae's middle name has not yet been announced.

Erin, who also shares 3-year-old daughter Helen with her husband, explained that the moniker was revealed when Sullivan's character was trying to pick out a middle name for his baby's name on the show.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

"An Easter egg from our friend @sullivangrams: earlier this year on @nbcthisisus, Kate and Toby were at the hospital awaiting their baby," Erin wrote alongside a photo from the episode. "Our friend Chris, who plays Toby, was writing down ideas for the baby's middle name and he snuck Mae (and her middle name!) in there to see if we would spot it when we watched the episode. 😄🥰"

Baby Mae's name wasn't the only Easter egg hidden on the list. Sullivan paid tribute to several other people relevant to the show, including This Is Us creator Dan Fogelman and producer Ken Olin. Olin's wife Patricia (Patti) also made her way onto the list as well as the couple's daughter, Roxy. Sullivan's wife, Rachel, was also included.

Later on Monday, Ben, 37, shared a sweet photo of daughter Helen cuddling with her new baby sister.

"This is a very memorable Memorial Day weekend for me and my girls. #bigsgirls #memorialmae," the dad of two wrote.

Mae, who is named after Erin's beloved Aunt Mae, arrived at 8:23 AM on Friday, coming in at 7 lbs. 1 oz., and 19.5 inches, PEOPLE can confirm.

"While we are excited to have another daughter to love, we are more excited to see the bond she and Helen will have. They're already so in love with each other!" the couple told PEOPLE.

RELATED VIDEO: Erin & Ben Napier Share the Unexpected Way They Found Out She Was Pregnant "the Day Before Filming a Brand New Show"

Erin also shared the news of Mae's arrival on her Instagram, simply writing "Mae" with a heart emoji and a tag for Ben,, alongside three photos from baby Mae's first few days.

Ben and Erin announced their pregnancy news in April, telling PEOPLE at the time that they found out in September while simultaneously filming Home Town in Laurel, Mississippi, and their new show, Home Town Takeover, about 200 miles away in Wetumpka, Alabama.

The couple wasn't sure if they'd be able to start a family due to a complicated, years-long health battle Erin had faced, they previously shared with PEOPLE.

For a decade, starting when she was 19, the designer suffered from bouts of severe stomach pain that would leave her bedridden for days. She saw countless specialists before an emergency exploratory surgery in 2014 finally revealed the cause: she had a perforated appendix.

Her appendix had been bursting and healing repeatedly for years causing her organs to become wrapped in scar tissue and bound together. But even after doctors removed the tissue, she was told the damage done would make it unlikely she would be able to have children.

The Napiers were surprised to find out that they were expecting three years later — on Mother's Day 2017 — and welcomed Helen the following January. "There's nothing you can say that does [motherhood] justice," Erin said at the time of her change in fortune. She said in April that with her second baby, "I'm less nervous now. All is well."