The Reagan family is making a comeback — but not everyone’s returning.

CBS has officially given the go-ahead to Boston Blue, a Blue Bloods spin-off focusing on Donnie Wahlberg’s character, Danny Reagan, and his son, Sean. However, longtime viewers might be taken aback to discover that Andrew Terraciano, who portrayed Sean Reagan throughout all 14 seasons of the original series, won’t be returning to the role.

In his place, Mika Amonsen — recognized for guest appearances on Suits and Reacher — has been cast as Sean in the upcoming series, as confirmed by People. The reason for this casting change has not been disclosed, and Terraciano has not issued any statements regarding this development.

Terraciano, who appeared in 292 of Blue Bloods’ 293 episodes, had previously shared an emotional message when the original series concluded filming in 2024.

“It feels like, after 15 years, ‘family’ isn’t a big enough word for all of the people at Blue Bloods that have changed me, and helped me, and grown with me,” he wrote on social media.

“I am so unbelievably grateful to every single person that has guided me and provided me with wisdom and lessons that I will hold with me. Though it would be another essay to explain just one of the lessons or inside jokes that we have, I will never forget what I learned on that set in Brooklyn — ‘Run fast, laugh hard, be kind.’”

He added, “To the cast and crew, tell everyone you can how fantastic this was, because it was fantastic, and consider this a formal thank you to each and every one of you. I look forward to seeing everything you all go out and do. Sean Reagan, I let you go.”

Blue Bloods was canceled in 2024 after a 14-season run despite vocal protests from its stars. The show, which debuted in 2010, followed New York Police Commissioner Frank Reagan (Tom Selleck) and his law-enforcement-driven family.

Announced just two months after the cancellation, Boston Blue will expand the Blue Bloods universe with a fresh chapter set in Massachusetts. The series follows Danny Reagan as he takes on a new role with the Boston Police Department while Sean starts his career as a patrolman.

According to CBS, Sean has “relocated to Boston to start a new chapter as a Boston PD patrolman. Sean committed himself to pursuing his family’s legacy but wanted to do so on his own terms, which meant joining a department outside of his hometown. Danny’s decision to stay in Boston gives this father and son duo a chance to reconnect on a deeper level.”

Boston Blue is being written by Brandon Sonnier and Brandon Margolis. In addition to Wahlberg and Amonsen, the cast includes Sonequa Martin-Green, Gloria Reuben, Maggie Lawson, Marcus Scribner, and Ernie Hudson. It’s still unclear whether Tom Selleck will reprise his role.