You have recently added multiple contacts for a single customer. This does not resolve the issue for users. In large organisations invoices need to be able to be sent to different contacts. At present all KashFlow can do is send the invoice to contacts set as receiving emails.
When an invoice is created it should be possible to assign one or more contacts to the invoice so that it is emailed to to the right person. Also with recurring invoices it should be possible to select who the invoice is automatically sent to.