Two (Sub-)Domains with different IPs and one shared document root

[m.wohlers]

Hello,

I'm using Plesk 8.1 on a server with full root rights and have the following problems:

Domain "domain.com" configured in Plesk with, IP 1.1.1.1
Domain "additionaldomain.com" configured in Plesk, IP 2.2.2.2

Subdomain "sub.domain.com" configured for "domain.com" in Plesk => IP 1.1.1.1

Now I need the subdomain "sub.additionaldomain.com", which should use the same document root as "sub.domain.com" - but with IP 2.2.2.2, needed for SSL.

How can I realize that?

Or - at least - a domain alias with a different IP address, so that "additionaldomain.com" with IP 2.2.2.2 points to the document root of "domain.com" with IP 1.1.1.1

Thank you very much for your help!

Michael Wohlers