Rpg Maker Developers Group

Hello there! I have a question about custom skill costs for Yanfly's Skill Cost Manager ... (github link).
I'd like to create a skill for bow/crossbow-type weapons that costs arrows/bolts.

I know how to make a skill use items as "fuel", however, I'm using Selchar's Item Charges... (google drive link). This means I have Tsukihime's Instance Items as required by the former. With Instance Items, every single arrow appears as a separate element in the inventory, instead of stacking together, so I'm worried it will make the inventory be messy and cluttered, considering how many arrows the player may need to carry around.

I figured that it would be more convenient to have the player carry a quiver as a single item, and the arrows it carries would be represented by charges. Then the bow skills would have to cost one charge of the item, and not the instance of the item itself.
Now the question is, how do I set that up?

For example this is how to set the skill to cost an item via skill notetags

<custom cost requirement>
$game_party.item_number($data_items[1]) >= 1
</custom cost requirement>

<custom cost perform>
$game_party.lose_item($data_items[1], 1)
</custom cost perform>

But how do I make the skill cost one charge of an item? What do I write instead of "$game_party.item_number($data_items[1]) >= 1" and "$game_party.lose_item($data_items[1], 1)"?

Well, that's all I want to know, thank you for your time.