Sorry to hear about your issue. However I'm not sure why there would be an issue updating the name on VA legs. Either the name should be updated on all legs or none at all.

I wouldn't be arguing with VA about changing his name. I would instead argue with them that while DL has changed his name on the reservation, that it's not crossing over into their system. This is a VA issue, DL has done their part, now VA needs to figure out why their system isn't updating information in the VA system. They may need to recreate the VA system reservation (which is different from the DL reservation) if for some reason it's not syncing the VA and DL reservations.