There is an article from "New Beginnings" magazine, LLLI's mag for members,
Sept-Oct 1998 entitled "Breastfeeding a Baby with PKU".  Many articles from
the mag are on the  <A HREF="http://www.lalecheleague.org">LLL website</A>
(which is "searchable") although I don't know if this article is among those
on the site.  It might be helpful for the mom to read of another mom who has
"been there, done that".

Lisa Jones, LLLL in Wellington, sunny south FL