TxRose,
Did you take the prescription to the VA or a military pharmacy?
You said "I am told they only cover generic medications unless (and only in some cases) a VA doctor prescribes them", which makes me ask if you tried. I have folks in my family who are surviving family of veterans, and at least on Tricare, the limitation has nothing to do with generic status or prescribing physician, but with what the military formulary allows. If the drug is on the list, they provide it. If not, you are on your own. And that 'on your own' situation happens, but I would be sure that they actually refuse for a valid reason, so that you have indication on how to get it fixed.
I would ask for clarification from the VA.
And, by the way, Welcome to HW. I hate to see that your dad has to get back into patient mode. We all dread the day that PSA starts back up.