One skill that is pretty necessary as a foster parent is being creative in how you get the necessary tasks of life done.
I have had two little girls now, both around 2 who came to me with an extreme hatred of bath-time. The thing is I can't just not bath a child and I think bath-time can be such a great sensory, fun time for kids if they can settle in and enjoy it.
The solutions although different worked with both of them. The goal is to always observe as much as you can about the child when they are tantruming - to try to figure out the problem and then just start trying different things. Not everything will work, but most likely if you can keep your head on straight and remain calm, you will stumble onto a solution.
So once I watched the terror in both of them, and what it looked like and felt like, I tried some things.
With kido number 1 it seemed like it was more a fear of getting undressed then getting wet. First of all, I started doing her baths upstairs, in the kitchen since since she was small and the bathroom was a pretty unknown room, whereas the kitchen we spend a lot of time in. Then, for about a week, I put on a new diaper and a onsie on and sat her in the sink with water and toys. I took it super slow, washed her arms only the first day, then her arms and her legs, then we washed her hair. After about a week, this seemed cool with her. She was enjoying "tubby-time". Then I took of the onsie and just bathed her in a clean diaper. Then after about a week, we did a bath the way its sposta happen, in the buff, in the sink. She loved it. Once the splashing got out of hand, I mean she was 2 and now loved the bath, I started doing baths downstairs in the tub. She made the transition no problem.
With kido number 2 she did not want to get wet and hated the feeling of the water by her or heaven forbid on her while washing her hair. But, her close in age sister loved, loved the bath so we started doing baths together. She still wasn't a fan, but I would get about 10 seconds of no crying by pointing out how much fun this is, how good it is to get clean, etc, etc. Still no fun, but an improvement over the clawing, screaming, terror. Then I remembered how much she loved drinking anything out of a straw. So I brought a big glass of water with a straw into the bathroom with us. Once she was in the tub for those 10 seconds of no crying, I broke out the cup and asked if she wanted a drink. Through her tears, she started drinking. "Hmmm. Yummy.... :sign for more:". We all take drink and she has some more, about 5 minutes of no crying, actually starting to explore the tub, but then we had to wash her up - out the second we were done. Another night, I brought the cup again and some fruit snacks. We had a drink and some snacks, while I was pointing out all the toys, talking about how much fun bath time is, etc. Then I washed her up. Still didn't like that, but you know what? Once we were done, she played in the tub for about 10 minutes soaking wet, loving every minute.
I could tell you stories for hours like this. Even when the behaviors are similar, the solutions look totally different. So look at your kids when they are melting down today, try to figure out the root and start from there. Not to say this eliminates all issues, but it helps me. It gets me out of the one response for every child rut that I get into. All children, all issues are different - and all need different solutions. So be creative, have fun and keep at it. You can do it.