My client has asked to be able to modify the currency on mrp.bom.line items. We added x_currency_id to mrp.bom.line and made it a computed field equal to the currency_id of the product_id. 

This correctly displays the currency of the product. The problem however is that the currency of the product is a computed field. So no matter what we do we can not modify the value of the currency of the product as it is always the company's official currency.

Is it necessary that the currency of the product must be the default for the company. I understand I have the power to change this if I want. However if this would open more complications (accounting,inventory...) then I would obviously leave the definition of the currency of the product and simply break the association for mrp.bom.line whereas I would no longer make it a computed field, I would simply set a default based on the product and if someone changed it then so be it.

If anyone could lend me their input it would be greatly appreciated. I have my reservations about modifying a field which is such a core component however if it will not break anything and it will make my client happy then I don't mind. 

Please share your thoughts, and reword your criticisms as playful banter. 

Thanks!