Anna, if the mother originally brought in a normal milk supply and
established it, she may, without too much trouble, bring back the milk with
mechanical means (pumping, a willing baby suckling.) I have worked with many
women over the years who have done this. However, if she experienced
prolonged engorgement during lactogenesis, followed by involution and
atrophy, she is really not so much relactating, but inducing lactation.
This can have less predictable results.  In such a compelling situation,
where the baby's health and perhaps life are on the line, she may want to
consider some of the hormonal protocols.  Lactation consultants working with
MDs may be able to assist.
Hope this helps.
Barbara

Barbara Wilson-Clay, BS, IBCLC
Private Practice, Austin, Texas
Owner, Lactnews On-Line Conference Page
http://moontower.com/bwc/lactnews.html