Do I have to throw out all of my old family recipes?

Who hasn't noticed that package sizes have been decreasing in size in lieu of price increases? How do you deal with a recipe that calls for a 16oz can of something but is now only available in a 14oz can? Or a 6 oz package that is now only available in a 5oz size? Do you buy two packages so you can have the total amount of ingredient the recipe calls for? Do you reduce the overall recipe (all ingredients) by the same reduction percentage wise? If so, then what do you do if two or more ingredients are in reduced packaging sizes but by different percentages? For me, cooking and following a recipe is hard enough without having to deal with product sizes no longer available.