With 365, if you have alternative products you can set them to be recognized and recommend if you are out of stock through the "sell" settings in part setup.
To keep inventory levels low, is there a way to recognize alternative products when setting min./max. stock levels so that you do not carry inventory of all the alternative versions, but can select the best available/price unit to order in to put in stock? Then along with that when you run master planning it gives you the list of alternative products and you can select which one to fill?