All modern Samaritan High Priests originate from the line of Tzedaka Tsedaka II ben Tabia ha'Åbtå'i after the previous eligible line's last heir was murdered. Seeing as how Samaritans have a small population of under 1000 it is very probable that in the ten or so generations from Tzedaka we might be able to connect nearly the entire Samaritan population.
Connecting his lineage to Ithamar would be an ideal but nigh impossible task most likely, however I am interested in whether he may have had maternal descent from the older lineage