I am in the process of setting up an inventory system and have several levels of sub assemblies between the base components and finished products. Ideally I would want to be able to update the current quantity for individual components, then after I update the quantity of a sub assembly it would automatically fire a macro to compare the new and old quantities and update the component values accordingly.
If someone could point me in a good direction to get started I would appreciate it.
sounds like just simple formula (no need for macro)
It’s a database task. Nobody ever established such a thing on spreadsheets.
why wasn’t it marked as solution ? 
A solution takes dozens of hours of development work. My sample was just a hint, that there is another tool set made for this kind of problem. The spreadsheet that is marked as solution demonstrates that a spreadsheet can be queried by means of SUMPRODUCT formulas. This is good to know for an ad-hoc solution when you need to analyze a given data set thrown at you via email or csv download.