Kate Arthur in The L.A. Times has a great interview with Katee Sackhoff and David Eick about the elaborate methods they undertook to keep the real fate of Starbuck double super secret.
For Katee, not telling the truth, and keeping the secret from fellow cast and crew, and even from members of her own family, was quite difficult:
The animated Sackhoff found it difficult to lie to her fellow actors about what was going on. (Deceit doesn't seem to be her forte, generally speaking: In the first minute of this interview, Sackhoff admitted that she was hung over, because, she said, "I don't want you to think I'm stupid. I'd rather you think I'm, you know, a drunk.")Read the full article at The Los Angeles Times.
Eick soon realized that this part of the plan simply wouldn't work among the close group of friends in the "Battlestar Galactica" cast. "It wasn't fair to her," he said. "She was going to have to lie to literally everybody in the cast: 'Yeah, yeah, I know, it's awfully sad. I'm gonna miss you guys!' It got ridiculous at a certain point. She was a trooper; I think she would have done anything we asked her to. But she's not inhuman!"
So the cast was told that Sackhoff and Starbuck were there to stay, but anyone else deemed a potential leak was kept in the dark. Including Sackhoff's own father. "My dad has a big mouth, and I knew he would get on his e-mail list and tell everyone," she said.