Share 'B6 for Keppra'

I have a question I have sort of asked before. What is the better levelling range for added B6 for keppra issues? We are on 75 mg per day-I feel he is being stingy with the dose (he upped it from 50 to 75 mg- I have read much higher for kids smaller than mine).   Have any of you just added it on your own? My child is 55 pounds age 7. Thank you.