Sure thing! PTSD has within the dx itself, an element of dissociation. The pdoc has to know that already..so it won't be a hard sell, imo. I think you might be thinking that to have an additional dissociational disorder would be overwhelming to the PDoc...and I don't think he should shock him at all.
Many ppl with dissociative disorders also have PTSD. Not all of them need to be medicated though. I'm unsure as to why your T is responding as you suggest. I'm hoping you misunderstood the intent here, and that your T really is more knowledgeable about the link.
I'm not sure that what you are looking for is the PDoc's expertise, since you already see a T for the psychotherapy. Isn't the PDoc for your medication? If it's not a dissociative problem, then the PDoc could help you figure out what it is. If it turns out to be a DD, then the T is the one to help you find ways to cope until the issues are worked through, imo.
Don't fear anyone... they are hired by you to consult with you on what they think and what you should do.
TC