link between incontinentia pigmenti and erythema multiforme

My 24 year old daughter has Incontinentia Pigmenti.  Recently my 16 year old son developed Erythema Multiforme.  We think the cause was Minocycline which he was taking for acne.  Since both of these disorders are quite rare, the IP being more so, and they involve similar skin rashes, I was wondering if there could be a link between the two?  Also, my dad had several nasty bouts with Pyoderma Gangrenosum when he was ill with heart disease and colon cancer.  To top that, my sister survived a terrible episode of necrotizing faciitis in the mid 90's.  Her Drs. in Boston think that she may have also had Pyoderma Gangrenosum when she was suffering from the NF, because of the fact that my dad had it later.  They did not consider that at the time as it was not a factor yet.  I do not have IP, but often wonder if I may be a carrier.  Lately another sister's grandchild is having some immune difficulties and is currently being worked up for them.  I have to wonder if we are all carriers in my family as IP is associated with immune problems.  Can anyone enlighten me here with any research or more info?  Thanks!