Hello,
We had the SAME issue with our 3 1/2 year old son. As you are not against bribery and rewards, I'll share our process! My husband and I went out and bought a whole bunch of little toys, some where sets that we seperated, like a small pirate ship and all the characters and treasures chest, etc. We explained that this was his prize box and that he could pick a prize everytime he pooped on the potty. Well, that took all of 15 minutes! He never looked back. The best was that he first chose the little pirate ship, then he wanted a pirate to sail in it...he had to wait till he pooped to get it. Then, he got that and wanted the little pirate fort that was in the prize box. By the time the prize box was empty (2-3 weeks) he was poopy (?) trained! Once the box was empty we didn't refill it, but would have if he was still having issues. It cost us all of about $15-$20 dollars. So, the castle reward she wants must seem intangible to her. Maybe you can find a little castle set, bread it all apart and add a few more trinkets...you'll have yourself a prize box. Wait until you get it all together then tell her the guidelines for earning it. You may wait until the late afternoon one day, as she has been going in the evening.
My son was also all about the control...well this gives them the control over something else and takes the spotlight off the actual pooping.
Good luck, it will be over before you know it and you'll be diaper free!