At first I thought, I wondered if using the non-dairy powdered coffee creamers and adding just enough water to make them the proper consistency would help, but I realized that the chemical reactions in the recipes would probably be negated by doing this.
I sympathize with those cooks who have to constantly modify recipes for health reasons, and I don't have any answers for this lady other than to suggest that she should probably look for compatible recipes to those she wants to prepare. Let's face it. If she's allergic to milk products, she is NOT going to replicate granny's pumpkin pie. It's just not gonna happen. That doesn't mean she has to give up pumpkin pie! There are non-dairy versions available, just as there are non-dairy versions of many things. But not all things.
My suggstion to the lady is to stop trying to replicate recipes using substitutes and start looking for tried and true recipes that she CAN eat. It's one thing to say, "I need a substitute for this ingredient that I cannot find." It's a whole other ballgame when someone says, "I need a substitute for this ingredient that will make me sick."
I don't trust anyone who needs a recipe to make tossed salad.