There's been comment on Firefly Jar consolidation--some for, some against--but my suggestion is aimed toward other bottles and also jars, such as potions and powders. For instance, I have two bottles of Door Potion, one is 2/3 of the way full, the other is 1/3 of the way full. It would be great if I could pour the 1/3 into the 2/3 (or vice versa) in order to free up a bag space. Furthermore, it would be really helpful to do the same with Random Kindnesses. If a player finds or has been given a partially used rainbow, combining it with his or her current partially used rainbow would also save space.
This is a different issue from Firefly Jar consolidation, as this has nothing to do with extra work. It's simply a matter of combining what one already has.