You can and if it gets enough votes, our developers could take it into account
There are few things that I don't understand in this request though and some obstacles that I see
- what would be the use case for this
- why would you send birthday email to the person who has the birthday and also send the same email in CC to someone else
Also, AcyMailing can send email only to the email address that exists in AcyMailing as (confirmed) subscriber. This would fail if you would want to send email in CC to someone else who is not a subscriber in AcyMailing and is also not confirmed (if you require confirmation)