Mika Amonsen will replace Andrew Terraciano, who played Sean Reagan throughout the 14-season run of "Blue Bloods."Though Donnie Wahlberg is the only member of the core Blue Bloods cast set to return for the long-running series' first spinoff,

Mika Amonsen will play Sean Reagan in the 'Blue Bloods' spinoff, 'Boston Blue,' a role previously played by Andrew Terraciano.

CBS’s upcoming “Blue Bloods” spinoff has recast Danny Reagan’s son after the same actor played the recurring role throughout the original 14 seasons. Andrew Terraciano will not return as Sean Reagan in “Boston Blue” after appearing in nearly every episode across 14 seasons as the son of Donnie Wahlberg’s character,