My grandmother was a vet, who moved to be closer to her grandchildren but my grandfather was buried in a veteran cemetery back where they were originally from. She went to a reputable funeral home where sh burial would be buiried to pay for that end. However, where she would die did all the arrangements for embalming, her casket, and travel arrangements home. However, I know from long distance, your local funeral director can make arrangements for both ends, especially if distance is an issue to make the arrangements for both ends and pay in one place. There are very specific requirements for shipping persons that the funeral homes are aware of. They can take care of that as well as applying for permission to be buried in a vet cemetery. Visit a funeral director to talk to them about his wishes.
Unfortunately, most veteran cemeteries are on a first come basis. They try to keep a family together if there is room, but otherwise there is no guarantee unless you buy a plot, then you are not necessarily buried in a veteran section and it will cost, but you will be guaranteed a spot. It is frustrating. Perhaps this has changed as it was a couple of years ago but definitely look into it.
As far as your partners wishes, if the arrangements are made the way he wants ahead of time it is harder for them to make changes. If he makes a will appointing an executor, can be family or a friend

to make sure his wishes are followed, this will insure that they cannot change it legally.
It is not easy when family has their own ideas than what the loved one wants. I know we went through that ourselves with some of our relatives. It is maddening to know someone's wishes are not being respected and heart wrenching. It is lovely you are helping him to sort through this. My thoughts are with you.