How do I track a charge used on a spell, more details inside

[Senko]

I'm trying to make an item that has 3 charges a day and 2 spells that can be used. Use spell A and it consumes a charge, use spell B and it consumes a second one.

I've got most of this working spells, charges per day etc but I can't seem to link them. That is if I look at the item on a character I see . . .

Under "tracked resources"
<0/3> Item (3/day)
Under "In Play" - "Tracked Resources"
0/3 item (3/day)

then further down under "In Play" - "Item Spells"
0/3 Beastspeak
0/3 Non-Detection

Which is where I hit my issue I can't figure out how to link the 0/3 of item spells to the 0/3 of tracked resources so when I increase the tracked resource value it affects item uses but no spells like so . . .


Under "tracked resources"
<1/3> Item (3/day)
Under "In Play" - "Tracked Resources"
1/3 item (3/day)

then further down under "In Play" - "Item Spells"
0/3 Beastspeak
0/3 Non-Detection

Whereas what I want is . . .


Under "tracked resources"
<1/3> Item (3/day)
Under "In Play" - "Tracked Resources"
1/3 item (3/day)

then further down under "In Play" - "Item Spells"
1/3 Beastspeak
1/3 Non-Detection

I know it can be done as the wands function like this but I can't see any special scripting in them I can adapt to do this. So can anyone explain to me how I can set it up so the spell count increases along with the tracked resources?