@KYguy You can't really offer them food. I've noticed more success by dropping roaches into their enclosure to cohabitate. I don't drop in too many roaches (1 for each specimen in my communal), and keep them on the smaller side. I'm not worried about my specimens getting ate up during a molt because they're adults and won't molt again. I wouldn't do this with younger specimens, for my younger C. gracilis (2i and 3i) I pre-kill and leave it for them. They'll munch on it.
@miss moxie I have been having better luck with just leaving them roaches. I think the only problem I am having now from time to time. is the roaches seem to hide in the artificial plants lol. So if they haven't eaten them after 2-3 days. Ill try and corral them over to the scorpions and seem to be having better luck. Thanks