Hi Nate,
Not sure I've understood you correctly, but here are my thoughts.
1. You can try to set up your matching rules the way both "server goes offline" and "up" messages are sent to the same group. Probably your UP messages contain some specific words (subject, body, from, to) you can tell them from other ones. In this case you have to go to Edit Source and set up your rules accordingly (see example below).
2. If your issue is related to on-call settings, see an example below:
2 PM - Jack is on-call
2:30 PM - server goes down and notification is sent to Jack
3 PM - Adam is on call
3:30 PM - the same server is UP and notification is sent to - you'd like Jack to be notified?
If it's your current issue, there's nothing we can do. If Adam is currently on-call, all the messages from source (including UP message) we'll be sent to him, not to the ones who got related 'down' messages.
Please inform me if there's anything else I can do for you