I'm sorry that all I have to offer is my sympathy but you sure have that.
If you already haven't you should read this article by Dr Noel Rose http://www.aarda.org/infocus_article.php?ID=28
I've never heard of a study which tried to determine if the genetics "double up" when two people with autoimmune disease have children. I'm sure you would rather not be involved in such an interesting situation, but it is interesting.
I thought this statement from the AARDA related to Dr Rose leaving the AARDA to accept the position as Chair of the NIH Autoimmune Diseases Coordinating Committee was interesting, accurate and not something most people are aware of:
There are more than 80 and another 40 suspected autoimmune diseases. They all share the same underlying cause - autoimmunity, the process by which the body's immune system turns on itself, attacking healthy organs, tissues and cells. Approximately 50 million Americans suffer from one or more autoimmune diseases. Of those, nearly 75 percent - or roughly 30 million - are women. Autoimmune diseases include lupus, multiple sclerosis, juvenile diabetes, rheumatoid arthritis, scleroderma, Sjvgren's disease and Graves' disease.