Soymilk cream sauce
Can you use Soymilk in making a cream sauce or is it too checmically different from normal cow's milk?
No need to use milk at all. You can use chicken, seafood or vegetable stock to make a velouté, rather than a bechamel. They're very similar. Both start with a blond roux and then liquid. So, yes, the soy beverage works. Just watch for the sweet flavor in some of them which might be inappropriate.
It may depend on what type of cream sauce, but I've used Soy creamer (specifically Silk's "half-and-half") as a perfectly fine substitute in recipes calling for heavy cream, with good results.