How to determine whether a service was terminated (not running but it should)?

I've got some services in /service/... in a gentoo-based system and I'd like to monitor these services. I can check whether they are running or down using svc-status but how can I determine whether they are not running but they should? So they are stopped due to some error or were they terminated. Is it possible at all? The use case is that I have more instances of the same service but not all of them are running at the same time. So I'd like to get notified by my monitoring script whether, for example, 3 out of 8 instances are running only when I explicitly started 4 instances.