I know, Annasaur. It is very expensive. I wish stores had discounts for all of us
However, that is so sweet of you to be caring for them. Perhaps you can post pictures, we'd love to see all of your kitties!
Perhaps, your presence, from whichever distance your kittens are comfortable enough with you to eat, will be equally enough to deter the possum. Possums are scavengers so he won't starve. But, of course, he will come to a meal served on a platter by a generous student rather than work for it for hours
As for my feeding all of them together. I put out extra food since, like you I cannot afford but so much. I feed them only once a day out of the two 18 lbs bags + 10 cans that last 4 days. The great thing is that I buy it every other 4th day; me and my MIL cooperate and it helps!
I haven't seen any racoons throughout the summer. And a possum here and there. I think they will come back during cold weather.
Racoons are very funny because it sounds like they gossip as they walk towards the food. The funniest thing that happened to me regarding them was to see racoons and cats running shoulder to shoulder towards me, while I was laying down the food