Yes yes but is my suggestion possible?
1.is it possible to make one certain unit Only be supplyable by another certain unit?
2. is it possible to have limited supplieng capabilities aswel?
answer to 1 and 2: not with standard coding. A dedicated python script might be able to do the trick, but it might be quite complex to code.
The problem is that ammo sources reload
anything (from pistol rounds to battleship ammo, and for both sides too) in game within a certain radius. This is hardcoded AFAIK. You can test it with deployable MGs: when dropped they will replenish enemy tank ammo for example.
A python workaround might be something like "when driver of ammo carrier presses secondary fire button create an invisible ammo replenisher with an extremely small radius right on top of the nearest vehicle of type X, and destroy it after the (very small) amount of time needed to reload exactly 1 shell. Keep track of how many times the script is invoked by the same ammo carrier, after Y uses don't replenish anymore.".
In any case this would leave open the problem that any guy with an ammo kit could drop an ammobox (or a mortar or deployable MG) next to the SP artillery and fully replenish it. I guess you could limit this by not placing
any such kits in the map.
Problem is, I think there are a total of 2 python scripters in FH team, and as you might guess, there are better priorities for them. :\ Also, anything python means more server load.