Alison, I've heard the same thing as Kelly. I think if you've made a few sales to them, you're in a better position to negotiate the rights for a given piece, (for Carus.) This issue has come up in a couple of chats with Carus editors. If you check Julie Messina's transcript here, on Verla's site, and search the ICL site, you'll find some the info. first hand.
As far as the poem, my opinion...if Spider's max is 20 lines, I wouldn't send them more than that. Either edit the poem down to 20, or send it to Cricket.
Good luck!