My kids,when they are sick don't want to eat or drink much. We ususally have powdered gaterade on hand, and make it up using less than half the recommended amount. I also find that ice pops helps. They have sugar, but getting liquid into the kid is more important. The ice pops seem to sooth throats that are sore from vomiting, and because it is taken in slowly it doesn't seem to upset the tummy as much. They make pedialyte ice pops, but they taste terrible, salty and nasty. My kids wouldn't touch them.
I'm sorry about your girls. I hope they feel better soon.
To me, the worst sound in the world is that groan in the middle of the night right before the kid vomits all over himself and his bed. I don't think my kids have ever vomited during the day!