Add a new rule, Monster Inventories:

Monsters may carry items; this is known as the monster’s inventory. When an @ kills a monster, all items in that monster’s inventory move to that @‘s inventory.

Change:

Whenever an @ fights in a ranged encounter while wielding a ranged weapon, they decrease the number of that weapon they carry by 1.

in rule 2.5.2 to:

Whenever an @ fights in a ranged encounter while wielding a ranged weapon, they decrease the number of that weapon they carry by 1, and 1 of that weapon is added to the monster’s inventory.