Right on apb! I don't want to go in to too much detail on my patients, but I'm dealing with folks with similar ailments.
I have grown the Perkins cut. Calicat (as always) is corect, it's a Cannatonic pheno. It typically tests at 20% cbd, and <1% thc.
I prefer growing from clone when dealing with any epilepsy type ailment because consistency is key. You have to do your best to replicate the oil each and every time you make it. I have had great results with a dravet syndrome patient by using non activated oil. I do a dry ice sift of the bud, and then put the resulting hash in to room temp coconut oil. I make it at a ratio of one ounce of bud (the hash from it) to one cup of oil. I highly recomend trying it this way considering you're dealing with a kid, and parents that may not be too receptive to this. Once they see that their kid won't get high from the oil they will come around. I'm positive that this will work great for you assuming you find the right plant.
Good luck, and good on ya for doing this!