Generally speaking you can substitute goat's milk or other "milk" in recipes any time you want, there is of course going to be a different flavor, so that is the one concern. I don't recommend soy milk because of GMO soy and other issues but if you use almond milk that can be substituted in a lot of things without much trouble. I think it has a mild flavor. Rice milk may also be easy to substitute, but I haven't personally tried it.