Ha! Funny to see this resurrected.
Unfortunately, there really isn't any more to tell; it never really went any farther. As I suspected would happen, Sis and BIL never did anything further with this. I did ask her about once, several months later, and she said that they didn't do anything more (life has a way of getting busy and some things just have to slide), but also added that she couldn't wait to see if this woman tried to 'donate' anything again. If she did, Sis was going to tell the head of the donation committee about her experience the previous year, so hopefully Turkey Lady could be prevented from pulling the same scam on someone else.
If there is ever an update, I will be sure to let everyone know!
And funny...when I read about the cakes, my mind did flit back to Turkey Lady for a brief moment too!