One of the dogs I bred is a seizure assistance dog. He was trained by Paws with a Cause in Michigan. Paws has a website. It is my understanding that dogs cannot be trained to detect seizures, only to care for the person when they have a seizure. Some of these dogs learn to detect seizures on their own, but we don't know how they do it, so we can't train them to do it. Possibily someone else has more infomration on this.
A Tartan Plaid daughter which I purchased years ago, was retired and I placed her with a young couple with a 3 year old son. First off, the woman was diabetic. She would fall asleep on the couch and the dog would always wake her when her blood sugar was getting out of whack. Usually, her husband would wait til he noticed her coloring and just that "look" but Patty would always begin whimpering and lick her face frantically, to wake her. Then Patty starting acting the exact same way one day in their kitchen, but the woman was wide awake and her blood sugar was fine. Patty was focused more on their son, sitting in a booster chair, eating. Well be darned if he didn't have his first seizure right then and there. She detects both the woman's diabetes problems and the upcoming seizures on the child. All with no formal training whatsoever. The woman and her husband separated and the woman's mother emailed me to thank me so much for placing this dog with her daughter, how reassuring it is for her to know Patty is there with them.
I don't know where you are, but in PA there is a wonderful group called Canine Partners for Life. They know about this sort of thing. They may be in other states as well, but I know they are in PA for sure.
If you're in Western Canada, there are several groups that are training dogs for this type of work. One woman I know, has been training Bouviers for this work for quite a few years with great success! I hope this family connects with a local group & finds a good match!
CPL is an excellent organization...my wife volunteers there. Yes, some dogs do have the ability to detect seizures and each has his/her own alert signal.