Bro you really shouldnt use both products together. Ask Pp and he will explain. I'm not sayin it would be dangerous or anything but it would be a waste as far as I know. And speak to needto about discounts.
Now, for using Sustain after Dermacrine. Thats the way its supposed to be used except you shoud run a 2 month cycle of Sustain after a one month cycle of Dermacrine.