lindsay, i tend to agree with what tefer said on your other thread "Dead Hive" but also, please read my last comment.
in part from tefer:
"Getting the bees to consume the treatment is going to be your problem this time of year.
Most use some sort of drench, the bees clean each other ingesting the treated syrup.
Sick bees normally don't eat a whole lot, that's the reason you dump it on them.
It is to cold to dump wet liquid on the cluster for you.
I don't know the success rate for treating after the fact, but I assume that it's very low.
I would just let nature take it's course and see if some make it through.
Plan on replacing those frames and cleaning up the hive components."if one reads through oliver's research and writings to understand how fumagillin works and applications required and how nosema affects the bees, oliver does say this (to what tefer said):
"4. Depopulation and Collapse–Finally, the bees “lose ventricular function” (they can no longer digest food), stop eating (and stop taking medicated syrup, or pollen supplement), and simply starve to death in the midst of plenty. Most adults die far from the hive, leaving only a handful of young bees and the queen.
Colonies can collapse either during summer or winter, but the character of the infection differs. During cold season collapse, most bees are infected, and spore counts exceed 10 million spores per bee. Contrarily, under warm season breakdown, less than half the bees are infected, and spore counts are generally much lower. Forager bees just die in the field, and the colony shows no symptoms other than dwindling away."with the above said, i see no harm in trying it in fondant, given your situation, and would probably be willing to try for myself to see the end result.
good luck and best wishes. keep us posted. it's hard losing hives. for myself, for the times i suspected the bees died of nosema, there were plenty of honey stores. from my own experience and to what tefer has said from his experience and what i quoted from oliver, sick bees don't eat. this makes sense, when we are sick, we don't eat very well either. anyway, i hope this is not the case for you. it's worth a try. that's how we learn