Adding Quality Inspection param as weighted average attribute in target warehouse (Chemical Industry)

Hi All,

I am implementing ERPNext for a chemical manufacturer. They have a process wherein all incoming materials (Liquids/solutions) are Quality Inspected and then added to one of the available warehouses.
The Issue: The target warehouse may already have material. In such cases, the materials (liquids) are mixed and their final parameter is a weighted average (e.g. concentration of the solution) of previous and current addition.
How can I enable a customer attribute in inventory/warehouse so that along with weighted average price, the stocks will also have weighted average attributes values?
Do I add a custom fields in Material Receipt, Warehouse, and Item? How to set it up?