Right now all services for a client are billed in the client's "Preferred Currency" regardless of the currency/price selected for the service. Some clients may want to be invoiced in different currencies for different things. For example USD for a hosting service, but BTC for a VPN, etc.

The company defines the default currency, and we probably need to continue to have this defined for the company. But there should be some option, possibly on the client group, and at least when modifying a client, where the preferred currency can be set to None.

In cases where it's None, the client should be invoiced in whatever currency is selected for the service.

Some things to consider:

• If 2 services renew at the same time, and are different currencies, they cannot be on the same invoice. 2 invoices would be generated.
• We need to decide if we want clients in a group or in the company to default their preferred currency to "None" or if this would only be an option when changing an existing client's preferred currency.
• What are we missing? What implications does this have that have not been mentioned?