At least two true Reagans have reunited as CBS'Blue Bloods spinoff continues production on its series premiere.

As revealed on social media Friday morning, Bridget Moynahan is on-set in Toronto atBoston Blue, where she will make a "special guest appearance" as Danny Reagan's sister, Erin, in the offshoot's Friday, Oct. 17 premiere.

Moynahan will also direct a Season 1 episode ofBoston Blue, as she has done thrice before onBlue Bloods.

A "universe expansion" of the long-running family/crime drama, Boston Blue (airing Fridays at 10/9c) finds Donnie Wahlberg's Danny Reagan taking a position with the Boston Police Department. There, he is paired with Detective Lena Silver (Star Trek: Discovery's Sonequa Martin-Green), the eldest daughter of a prominent law enforcement family.

TVLine previously reported that Danny will not be the only Reagan family member relocating to Boston.Mika Amonsen (The Republic of Sarah, Hudson and Rex) has been cast in the series regular role of Sean Reagan, Danny's youngest son (of two). In Boston Blue, Sean has moved to Boston to start his own new chapter, as a patrolman for the Boston PD — thus paving the way for his father's own move.

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