Yes you can buy the gravy to put over the food.
Or you can just pour some homemade beef or chicken stock to mix in. Im sure its alot cheaper and healthier, seeing how IAMS isnt very good, I cant imagine their gravy being very nutritious either.
Just boil chicken or beef with water, save the broth, and you can freeze what you dont use now.
But watch for soft stools, if it does, cut back on the amount you do use, or you may not be able to use it at all. It just depends on the doggie.
Why is your baby getting picky? Is someone giving too much human food?