Hi Bob
Jst a small clarification on what you asked for. Namely that PHD2 does not synchronize or control dithers. It always expects the imaging application to tell it when to dither and the parameters to use.
Apologies if you already know this but a lot of people think PHD2 initiates the dithering.
So your imaging application would need to control the DSLR through Stargo AND interface to PHD2 to tell it when to dither.
-- Ken
Avalon M-Uno; GSO RC8; ASI1600; Optec focuser; Aaeon UP/Ubuntu/INDI