In every recipe and nested recipe you have the option of informing Parsley that the recipe is a “basic unit”, by clicking on the selector next to “Recipe size is a basic unit”. When you do that, Parsley will always scale the recipe in whole multiples of the basic unit. For example, if your 8-portion pie recipe is set as a basic unit, and you need 20 portions, Parsley will automatically print out a recipe for 24 portions (three pies), instead of a recipe for 2.5 pies. It will also create a purchase order for 3 pies.
In the example below, for a 6-portion quiche, we've set the Basic Unit to be a 6-portion quiche. If 8 portions are needed, the recipe will automatically scaled to 12 portions for recipe printouts, for event costing, and for ingredient purchasing