Hello! As a new duck owner, I don't have a lot of knowledge so I may be wrong. But my 6 weeks old duck started having those symptoms: seizures, imbalance, and the wheezing, after those she stopped eating completely. When I took her to the vet we got an x-ray and we found out that she ate a metal. The toxicity of the metal could be the cause of seizures and weakness in a waterfowl; if you think that it may be the case, you could buy a catheter syringe and feed your ducklings some peanut butter give them a lot of water, it worked with mine the seizures stopped and we could save her without the original treatment for it (the vet didn't have the injections).
Either way, good luck! I hope your babies get better
Either way, good luck! I hope your babies get better

