A Battle of Wills and Reverse Psychology

Allie is one we constantly have to battle about eating. She is very picky. Very. Today she had yogurt which she likes but after eating about 3 bites she wanted to be "done." I told her she had to eat it all. For one thing, it was a small container and I didn't think that was too much to ask. Secondly, it was one of those annoying containers with the foil top so I would have either had to ditch it or put in a separate container. After going back and forth, I told her her baby brother was eating his, thinking (for some odd reason) that she might be persuaded to eat hers. I don't know why I thought this as it's never worked before. To this she replies, "He can have mine." Stinker. We continued to sit and argue over this yogurt and informed her that was eating if she intended to get up from the table. After I saw this would work I tried a different approach. I took it from her and informed her that she couldn't have it. I also told her she couldn't have it anymore because she didn't eat it this time. It was gone in 5 minutes. Now who's the master of reverse psychology? Ha!