When Tantrums Backfire

Yesterday started like any other day. We went through our morning routine and then decided to go to the pool. The neighborhood pool is more enjoyable before lunch, since most people wait until the afternoon to go for a swim. We started getting ready. All the girls put on bikinis. Unfortunately, Sue Sue's bikini was too big in the bottoms. I knew if she wore it, she would constantly lose her bottoms in the pool. So I told her to find a different suit. You would have thought I told her she had to give up her a coveted toy. 
She began screaming at the top of her lungs. Actually, it was more like screeching. First I tried reasoning with her. Then I tried ignoring her. Then I tried to simply put her in a bathing suit. She tried to take it off. Then I told the girls we weren't going swimming. This resulted in tears from everyone. I quickly realized it wasn't fair to punish the other three for one sister's poor choices. 
In the end, I forced Sue Sue into clothes and told her she would be joining us at the pool... from the sidelines. I was a little concerned she would throw a new tantrum at the pool. She whined a bit as she sat in her chair. She constantly told me "it's not fair." I pointed out that it wouldn't be fair to make her sisters stay home just because she was naughty. Eventually she apologized and was quite disappointed that I wouldn't even let her put her feet in the water.
All in all, I think she realized tantrums won't get her anywhere. She is currently upstairs putting on a bathing suit to go swimming today and I haven't heard a single argument.