the microtoads will have a *much easier time eating melanogasters than hydei and you should seek those out.
you'll want at least a couple cultures; don't feed out all the flies at once or the culture will crash.
youl can feed the maggots from your arrived-upside down tub to the toadlets; they'll gobble them like candy.
i get mine from josh's frogs but they were out as you noted; last i checked they were getting more melanos july 3rd or so, so worth an inquiry; they respond very quickly in my experience.
Heather, did your survivors all survive?
i hope things turned out ok.