I forgot to mention that when I target event to a specific process instance (e.g. ksession.signalEvent("Signal", null, 1);), that process instance runs to completion (and is deleted from PROCESSINSTANCEINFO database table), and other processes continue to exist.
From the behavior I've seen it looks like process instances do exist regardless of their parent knowledge session, which is weird as process instances are created on session object....
Thanks,
Miljenko