Please forgive me, but I'm getting excited here... I may have connected some dots that were left unconnected before...
1: In "Ardashir and the Sasanians' Rise to Power" by Dr. @tourajdaryaee & "ReOrienting the Sasanians" by Dr. @sasanianshah I did not see these connections.
2: For some reason various sources note the name of a "Indo-Parthian" ruler as "Sasan", for example ...
in "Problems of Chronology in Gandhāran Art":
and "The interrelation between Indo-Parthian and Kushan chronology", 1992. This second article seems to provide some clues: