Need different but default Reply-to/From headers for specific mail accounts

Question

I just migrated to a rMBP-15 from a Windows/MS Outlook environment. I love it so far. Just to be sure, my OS is OSX Mountain Lion 10.8.3 and Mail is 6.2
I am trying very hard to replicate below mail account setup scenario using Apple Mail. I have two issues.
I have 3 Gmail accounts - lets call it G1, G2, and G3.
Issue # 1:
I need to setup corresponding accounts on Apple Mail (say AG1, AG2, AG3) such that when I reply to emails in AG1, the Reply-to and From address fields in  my outgoing emails should be G1, and when I reply to emails in AG2, the Reply-to and From address fields in my outgoing emails should be G2. In this scenario Apple Mail always seems to default to only G1 (or G2, or G3) depending on which one is at the top (default). Even if I set up corresponding SMTP servers with respective email addresses, outgoing emails do not get transmitted unless I choose the default SMTP server, thereby resulting in always a single Reply-To and From email address for all my Apple accounts.
Issue # 2:
I have a forwarding email address (lets call it FEA) issues by my grad school that I use to forward to G3. When I use AG3 on my Apple Mail, I like to have a Reply-to and From address of FEA.
How can I resolve the above two issues? I was able to easily do this in Outlook. All my hours of online research points to only the Apple scripting command "defaults" that will change the Reply-to header for ALL my outgoing email, but not for specific accounts.
I am happy to provide more details if required, but please any help is appreciated!!

Answer 1

This is not possible with Apple Mail (although its possible with Outlook). So, with some additional research, I solved this by myself as follows:
For the Mailbox needing a different Reply-to and From headers, I logged into corresponding Gmail account directly, and then
1) Went to Settings
2) Accounts and Imports
3) Under Send Email As: I clicked on "Add another email address you own"
4) In the popup, I entered the email address I really wanted in my Reply-to adn From headers
5) Clicked on Next Step
6) I chose "Send through <yourdomain> SMTP Server" and click Next Step
7) Here I enter the details of my ISP SMTP server (smtp.verizion.net, Port 465, my userid/pwd)
8) And then back on Goggle Settings->Account and Imports I choose this email as the Default (I will have to validate the email address by entering a code I get on that email)
I am done.
Now I can use Apple Mailbox with a Gmail account, and never have my Gmail address appear on ANY emial to/from this Mailbox account. I do not even have to choose "Reply-To" header everytime in my outgoing email.