Hi there, 

Glad to have you reach out to us here. QuickBooks is a versatile program that's designed to help you streamline your work. I'll be happy to show you how to send an invoice to more than one email address so you can save time.

The program allows you to send an invoice to multiple email addresses by doing either of the following:  Typing in multiple email addresses separated by a comma and space. Using the Cc (carbon copy) or Bcc (blind carbon copy) fields. For example, when creating an invoice, in the email address section, you can enter the first email, then a comma, and then enter the other email address. When you hit Send, the invoice will be delivered to both email addresses. 

Give this a try and let me know how you make out. I'll be one message away in case you need anything else.

Yes. Two options. Top of invoice under email of client you can cc' another client with a  different email and also send a blind copy bcc. Option two, when adding a client who may have been referred by another business person but you are billing direct, you can click sub - client when adding the new client and both will receive or can be sent a copy.