Go talk to General Alix first, as you only have a certain amount of time to arrange the escort for the healers.
This was not my experience. I wandered around doing several quests and clearing out thugs and orcs and I had no problem arranging the escorts in my own sweet time. Perhaps there is some kind of switch where there is 1 particular action wherein if you perform you have a problem in arranging the escort for the healers.
Cleglaw