I'm so very very sorry you lost some. That's so sad. Seems like your doing everything right. As long as they have a place to warm and cool as they need the others should be alright. I would give the nutri drench and maybe go in a few times a day and make sure they are eating and drinking. When you unpacked them from the box, did you dip each ones beak into the water so they know where to go to get it? ALSO each week drop the temperature by 5 degrees until room temp. If they are not eating maybe try a bit of boiled egg? I really hope the others do well. I don't think you did anything wrong. Sometimes the stress of shipping and the trip is difficult on them. Keep us posted and I hope all goes well.
I have a good friend in USPS, and he always remarks that it's amazing there is any that live at all.
They have to be shown food and water, it's what a mother hen would do. Not that instincts don't help, they (quite literally) have no idea what food or drink looks like.