infinity enchant for crossbow

infinity enchantment doesn't work for crossbow(even if I enchant for command it still use arrow)

so I trying to make New enchantment for crossbow which not reduce arrow in inventory.

these are what I want to know for create new enchantment

1. is there a check trigger for shooing crossbow? or using arrow?
2. My idea is before reduce arrow after using crossbow, I add new arrow to inventory, is there a better idea for that?
3. if I use 2. idea, How I check arrow in inventory and Add Arrow with checking multishot level and add multi arrows as multishot level