I have no experience crossing White strains, but they all come from the same ancestry and the way genes combine you are likely to get less potency than the parents had during the 1st cross. Cross it with something totally Different, like Super Skunk,or B52 and I bet you strike Gold.
You should grow out any seeds you might have gotten from the white crosses. Alot of people don't do this and miss out on the recombination of gene's. The F2's (seeds) "sometimes" turn out to be killer and most people toss 'em figuring they're junk. Always grow out as many as you can.....Although, 50 plants/seedlings is the Federal limit for sentencing and each is then considered 2.2 lbs.??? for sentencing purposes. "Keep those most approaching the Ideal and Reject all others", Quote from Luther Burbank; Breeder Extraordinaire.