I feel like this is a question that should have plenty of coverage, yet I found nothing that explained this to me in a way that I understood.
It may be (and feels like it) that I misunderstood something very basic and thus can't make sense of information that I got, so in that case: Please explain my mistake.
I have an OpenPGP key for my primary e-mail Address. It works fine, I can crypt, sign, encrypt messages.
Now, I also have a bunch of other addresses (one for business purposes, one from a political party, etc.) that I want to use the key as well. As far as I understood it, I can use one key for one Address and thats it. I can (somehow?) add subkeys for other addresses that use the primary key internally somehow.
So, when I send mail from my second account and sign it, I would not want it to show my primary email, but rather my second one. The goal would be that my business contacts get proper signed mail but do not obviously see my personal primary email. If they would need to lookup the key on a keyserver to see my personal address that would be fine, I just don't want to confuse people (got email from af@business. but signed from af@personal.)
Do I need to have multiple master keys for that or can I use one and add subkeys to it that have their own email addresses attached?