Easy enough to do the filtering with a for loop after I have the list of active acked alarms.
def listAckdALMs():
#get the list of all acknowledged alarms
alms = system.alarm.queryStatus(state=["ActiveAcked"])
#initialize empty list of sources
sources = []
#active ack'd alarms count is non-zero
if alms is not None:
#for each alarm, get the source path and add it to the list
for alm in alms:
if not (alm.activePipeline == ''):
sources.append(alm.source)
return sources