Ability to copy non user contacts into merge document email

It would be great if the merge document email platform had the ability to be able to copy the email to other contacts within aXcelerate. At the moment we can only send a copy to another user. It would be more useful if we could select a non user contact as well (for example a manager of a client). I understand this can be done through templates however the templates section is too restrictive for some of our communications.

An alternative would be to have the ability to select more than one contact under the 'single contact' option.