Managing domain between DH and non DH servers


Presently, our web server is hosted on a non DH dedicated server, where we also have a lot of other services (mail, svn, etc.). We want to transfer only our public web site to DH, but keep all other services on our dedicated server. In this scenario, we want that all requests to point to our didicated server, but requests to point to DH server.

The problem I see is that when I create a domain on DH, it assigns automatically an ip for the main domain and there is no way to change it. Is it possible to bypass this behavior? I know I can create a custom DNS record, so I can add an A record for that points to our server. But it doesn’t replace the A record created by Dreamhost, so I wonder which one will be in effect on a dns lookup.

Thanks for any help on this!