As predicted, an all-Shepherd crossover is in the works at Shondaland.

Grey's Anatomy's Derek (Patrick Dempsey) and Private Practice's Amelia (Caterina Scorsone) will be repairing their relationship in the upcoming season of Grey's.

Caterina, who was just promoted to series regular on Private Practice, will appear in the third episode of Grey's this season, Shonda Rhimes confirmed to TV Guide.

The premise is simple: Amelia Shepherd goes to Seattle to reconcile with her brother, Derek. The two Shepherds have not been on speaking terms since Amelia turned to drugs while grieving the death of her father, who was shot and killed in front of her and Derek.

Derek and Amelia will reunite this fall.

"Family is family," Scorsone says. "Regardless of the strife and tension and drama between the family members, there's a connection that is so deep. Obviously Amelia has a lot of emotion surrounding Derek and that relationship and all the things they've been through together."

In an interesting twist, Amelia will be reluctant to head to Seattle to see her brother, though she'll get a supportive push from none other than Addison (Kate Walsh) to reconcile.

"There's a lot of unresolved emotions surrounding that whole relationship. Everyone can relate to that fear of confronting situations that may result in rejection," says Scorsone.

Grey's Anatomy and Private Practice both return Thursday, September 23. What are your thoughts on the Shepherds' relationship and the upcoming crossover? Discuss!

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.