Jack,

I though that one would be better used as a pacifier and the other a food
source.  I would caution the biological mother that her milk supply may
diminish if baby get food from out side source and because
we can not be sure about the quantity of milk if any the practice
could shorten her breastfeeding duration, just as supplementing anything
would.

Heidi Lunn, M.S., I.B.C.L.C.