I think, the notion of camp supplies only being used by active party members comes from EA. Back then, it was like that and people complained about that, so it was changed with full release or one of the patches.
Buba: No, the title is correct, you can give Esther the owlbear egg with a deception check for the reward. The githyanki egg is not marked as camp supply. And for your last sentence have a nun ringing a bell and cry 'Shame' following you
I never had the problem, because so far, I never killed the owlbear mum and come back to loot the cave after I gave secured Owlbert, but at the least, we should be able to select, what he gets.
There is a mod, that changes the egg from food to quest item, but with the modding situation being as complicated as it is, I would wait with installing it maybe.
