Oh man, i know how scary those are, i am of no help but, zatara may eventually be able to let you know when a seizure is coming.
Riley who is the lone surviving pup from morgans one litter, would tell tina, at least 2-5 minutes before grizzwald, her other newf she got at 6 weeks from a different breeder was going to seiz, he would go run and bark at mike or tina, and lead them to grizz, and than proceed to lay by his side, as if to keep him steady or from bumping into things.
zatara may be freaked at first but than may be a help to you guys to let you know when.
also the chemistry in the body changes shortly before an episode wich is why they can sense it.
if you can keep track of the seizures and try to figure out the trigger, you may be able to keep them from happening quite so often, unless it is epilepsy and thanit may not be possible.
best wishes and keep us posted please.