I learned today that the "von" part of the name is probably an indicator of nobility. I also learned that this von Jossa family was also called von Jazo. See below:
Monastery dedications
In 1304, parts of the four brothers Reinhard, Gerhard, Giso and Conrad from the von Jazo family were dedicated to the monastery . They were closely related to the Bickenbachers, inherited Konrad and Guda's shares around 1290, from which the Jossa office was formed, and around 1300 built Jossa Castle on the nearby Dagsberg, whose name was also used as a synonym for that of the castle. In 1322 the transfer of the great tithe from Jugenheim to the monastery was confirmed, approved by the feudal lord Gottfried II von Bickenbach. Gülten des Alsbachers followed in 1337(Aldisbacher) Court of the Bickenbachers by Ulrich I. von Bickenbach on behalf of his wife Elisabeth and his daughter Agnes, who later became Countess von Katzenelnbogen after her marriage to Eberhard III. from Katzenelnbogen. Confirmations were made for 1340 by the nobleman Gerlach Haelstein, in 1353 by nobleman Gizo von Jossa and in 1361 by nobleman Rabenolt von Tannenberg the elder to the monastery, which are evidenced by documents in the Lorsch judicial book.
SOURCE: https://second.wiki/wiki/klosterruine_heiligenberg
