If you have one child with SWCAH it is almost impossible that the other will eventually surface with NCCAH.  There are separate mutations associated with SW, SV and NC CAH and in order for your child to be a salt waster he must have two salt wasting mutations because a person always presents with the milder form of the two mutations.

Just as there is a one in four chance that one child could get the defected gene from both parents there is also a one in four chance that another child will get both unaffected genes.

Hope this helps.

Risty