CBS has officially greenlit Boston Blue, a Blue Bloods spin-off centered on Donnie Wahlberg’s character, Danny Reagan, and his son Sean. However, longtime fans may be surprised to learn that Andrew Terraciano, who played Sean Reagan across all 14 seasons of the original series, won’t be reprising the role.

Mika Amonsen ( Thanksgiving) has joined the show’s cast as Sean Reagan, the youngest son of series lead Donnie Wahlberg’s character, Danny Reagan. Amonsen will take over the role played by Andrew Terraciano throughout Blue Bloods’ 14-season run on CBS.