The current event defintion for event uei.opennms.org/nodes/pathOutage doesn't allow to reduce the events on a single critical path:

That means, if a critical path is down, users will show an alarm for every nodes behind this critical path.

Also, there's no corresponding clear event, so users will have to clear all these alarms manualy.

Changing the reduction key to the following would allow event reduction on a single path outage: