How to derive price list based on sales order price list attached in EFF

Summary:

In our business case we have one Bill to Customer catering multiple end customer. The selling price of any item to Bill to Custome is depended on end customer. The end customer is not captured directly on sale order in any seeded field. So, we would enter/default the price list on sales order header EFF basis of end customer (again entered in the EFF). This price list should be considered for the item entered as SO line.