JDman,
You need a IMO " independent medical evaluation" to bifurcate the difference in your VA and OWCP claim..........For OWCP to have accepted your claim there was a trigger at work that caused the PTSD that was solely work related.
PTSD and depression go hand in hand in Most cases, yet they also can be separated by different effects such as you might be experiencing.
OWCP has a responsibility to follow the FECA, they can send you for a SECOP examine and then ask you to make a decision if the SECOP finds these injuries are one and the same, but you also have the right to your own medical opinion " IMO".
It is hard to direct you as there are questions between the two injuries and the cause and effect of both to separate the issues with PCP.
Just for if's.........you are kicked out of service for depression, as you don't like to be around other people, or another mild reason.........15 years go by and you are at work..........the boss or co worker come up to you and starts harassing you or threatening you in some way......this is a PTSD trigger in the work place.........you might be more depressed than you was before, but now you have fear, bad thoughts and such.
With this.......you have now separated your VA depression from your work related PTSD......Cause and Effect. Now you need a Doctor to explain in medical terms how they differ and why.