If you go with "secondary trauma" then many of us have tertiary trauma and so on and so forth. Trauma is trauma is trauma is trauma. It doesn't mater what the diagnosis is of the person who traumatized you, its still PTSD if you have a criterion A trauma. Your healing may be a bit different than someone who was traumatized in a bad car accident, but its the same with any two different types of trauma.
I think secondary trauma gives PTSD a bad name, period. It gives the impression that we're all horrible people who go out there and traumatize others, when nothing could be further from the truth. JMHO.
And, if you haven't been traumatized but are taking on the PTSD traits of a parent or caregiver, then its not "secondary trauma" in that there was no trauma....rather, it fits within another mental illness. Thus, you either qualify for PTSD with a criterion A trauma, or it isn't PTSD. "Secondary trauma" is a grey area at best and not an official diagnosis.