I am sorry your chicks had such a hard trip. Call your hatchery (if from one) and let them know as soon as possible. They will credit your account. Once I had a postal worker carry my chicks with him all day in January, his window open and they chilled. I lost almost all of them over the first 3 days. I would HOLD the vinegar and give them warm sugar water only. If you have electrolytes, add just a bit of them, but not enough to make the water bitter. Keep them warm and draft free, and watch for pasty butts. I use a tiny syringe and put a few drops of warm sugar water on their tongues from time to time if they are lethargic. Just be very careful and not give too much, they choke/asperate. you can use an eyedropper if you have one. Good luck, this is heart breaking. HenZ