Can Openfire be installed on a subdomain?

First, a little background before I ask the question:

Currently, I have Openfire setup on one domain, let’s call it “big.org”. I want to setup another Openfire server on “small.big.org”. The problem is that when this is done, big.org identifies small.big.org as belonging to itself, I suppose as the service “small” on “big.org”. So, people on small.big.org can send messages to big.org, but big.org can never send a message to small.big.org (since Openfire on big.org does not try to route the message externally).

So, my question is:

Can Openfire be setup to route messages to subdomains, or is this behaviour not allowed in the XMPP design?