Hi, your concern is reasonable here. Perhaps, you can seek the advice of her current cardiologist and ask for a recommendation to a adult cardiologist. This way your daughter will be happy not still seeing her "childhood physician" and you can rest assured hopefully since the new one would be recommended by the old one. On a side note...It may be a good idea for her to move to a new cardiologist as they would be seeing her with new and different eyes/perspective. Perhaps might have more insight into advanced treatments for teens/adults.
I am reaching here...but it really may be a good thing.