Dear Jan,
I can tell you my own experience with chicken pox and a nursing toddler.
 When my son was 15 months old my husband had shingles (the same virus).
 Several weeks later my three year old daughter came down with chicken pox
and I proudly thought my milk was protecting my son, who was sleeping in the
bed with his father and me at the time.  However, there must be a difference
between sleeping in the same bed and the intimate contact between siblings.
 My son succumbed to chicken pox another few weeks later.  Both children, by
the way had a fairly mild case.
Lesley Robinson, IBCLC, LLL Leader
Corning, NY