We have now only 3 groups of items in VA for loading inside uniform, vest and backpack: ammo for currently held weapon, all grenades, explosives and finally misc. items but only few types of them.
Right now you are very limited regarding adding items to uniform, vest and backpack.

Q: What if I want to add nightvision to my backpack?
A: I cannot do that.

Q: What if I want to make ammunition soldier that will carry ammo for my MG gunner?
A: I cannot do that cause I can only add ammunition for currently >held< weapons.

VA is good but it really can be better. There should be fifth category - show all items or magazines, that when selected will show all available ammo types so I can make my ammunition soldiers.