You could also try goat yogurt if its only cow's milk that's a problem.
Nondairy coffee creamer works, too, though I am loath to suggest it as a 1:1 sub for milk or cream, as it's not very healthy. Maybe, like Alix says, in combination with broth?
I cook for cow's milk allergy every day and I just use broth. I sometimes sub rice milk in baked goods.
Less is not more. More is more and more is fabulous.