Hello, I am new on this forum and I do not know everything about this condition but two years ago my son was diagnosed 9 days after he was born with CAH as well.  It was very confusing and stressing as well.  After the hospital assigned us to a great endocrinologist, we started to know more and more about this condition.  You can assure your daughter that once her baby is on treatment he is going to do just fine! My son is doing great. He is two now and he does has some sick days but overall he is doing just fine.  Tell your daugther to get involved with his pediatrician as well as with his endocrinologist. To ask as many questions as she can have that is what is going to help her get thru.  Ask about when to incrise dosages of medications, usually when they get sick, how to admisitrate medications to a baby, symptoms of dehydration, ask questions about charts growth on her baby, percentile growth. 

I really hope the best to your grandson and just give it time and he will be on the right treatment and you can see that everything will be fine!