Allow for multiple contacts in supplier and customers Merged

Currently I have a client with 17 contacts I quote to within their company but need to quote and invoice either to the contact or accounts. It is very time consuming copy pasting different names and emails all the time.

one way would be for the estimates and invoices to have multiple contacts like the deliver to address but when emailing it inserts the correct contact name and email address into the form, similar how invoicing works with the deliver to function.