We have similar situations. I have ITP and Lupus and my daughter has Graves. Anyone with one autoimmune disorder is more prone to develop another, or have a child with an autoimmune disorder as well. It can be the same one or a different one.
I constantly worry that my daughter will develop Lupus or ITP; both are common with Graves. However, I try to think positive and hope this is it for her and she will not continue on the autoimmune journey. Only time will tell.
Your daughter would be considered an adult now and could post in the adult section and in the Lupus section. We would be happy to have her with us!