While not paying close attention yesterday, I made some shrink potions. After I made them, I realized that the container I was using was a
Bearskin Potion Bag and not a
Medicine Bag. I was then able to combine my 10 potions into a single 10-dose potion, using the same bag. I didn't check any recipe other than the ant's potion.
While it's convenient to be able to do all this with one container, it's not classic. The bearskin bag should only be able to combine 5 or 10 single-use potions into one with the appropriate number of charges.