Apparently not

okay, so in a fight, you can see this icon:
Click it (or hit P, which is the shortcut)
this will open a sort-of-popup-screen that shows your party

there's a button in the bottom corner that says 'use item'- click that

select the item you want to use, and it will automatically go back to the party display, and the arrow icon's background will turn yellow.

click the pet you want to use the item on, and it will go back to the battle screen, with a little icon in the top corner of the pet's info box. The arrow icon will have a green background.

The item will be used once you hit the 'end turn' button.

(if you selected the wrong item or pet, just repeat the process)

Thank you!! Ill try that when Phantom and Prince Puff are healed :)