Hi! I was able to edit the invoice send email template, and add for the cc:

{{[i.email for i in object.partner_id.message_partner_ids]}}

Thanks! I added the contact person in the followers, but the email still says: Hello COmpany, please find attached... 

How DO I send to the contact by default? 

Hi,
Can you see who is there in the followers of the invoice record. You can click on followers(human) icon section in the chatter

Thanks