I have Blue Cross thru Screen Actors Guild and my husband has Motion Picture Health- both from our employment. My insurance picks up whatever his fails to supply, and the prescriptions division of Blue Cross (Medco) has his Copaxone delivered to the house Fed Ex every three months for $75.
He's had a bunch of expenses over the last year (MRIs, lumbar punctures, blood draws) and it's all been covered.
An MS diagnosis is still MS, no matter how old it is, it is still a "pre-existing condition" when she applies for US insurance, and will add a new layer to searching for health care. If your fiancee has work lined up before she leaves, that would be ideal.
Look into insurance policies for your own practice, and check out spousal coverage. I like Blue Cross of California, been good to my family.
Husband dx RRMS 3/07
dx dual jugular vein stenosis (CCSVI) 4/09