just to let you know i had the exact same ?? when my 4 month old swcah son was diagnosed in reference to my 2yr old and 4yr. old girls.  could they have the locah?? my girls, however, are not tall, just average for their ages. the endo stated that almost always the "gene runs true," so if it is the gene for swcah that you and your husband produce, it SHOULD only be that. obviously you would know by now if your 2yr old was a saltwaster. are you thinking of getting your 2yr old tested to see if she is a carrier?? i asked my endo about this and he did not feel it an issue until they are much older, but sometimes i wonder. best of luck!!

louise