Cynthia, I saw a mom recently w/large breasts and very large nipples.  The
baby would partially latch and then try to "spaghetti slurp" the rest of the
nipple into her mouth.  I had mom hold her index finger alongside the nipple,
and latch baby to both finger and nipple simultaneously.  With the finger
there the baby could not create suction until she was well latched.  At that
point mom simply pulled her finger out, leaving just the nipple.  It worked
like a charm!!

However...if mom has large breasts and flat nipples, I think I would continue
with the shield until the baby is nursing vigorously and well.  Mom should be
using a thin, silicone shield and baby can get plenty even if the nipple does
not fill the shield.  If mom has enough milk to pump and fill the
supplementer, there seems no reason why the baby couldn't get it just as
easily...then mom won't have to pump and mess with tubing AND a shield.  Mom
needs to know to keep her baby close enough that her nose actually touches the
shield.  If mom can see any of the shield's "nipple", she doesn't have enough,
and baby probably will NOT get enough milk.  Once baby is nursing on demand
and gaining well for a few days, then she can start weaning off of the shield.
 Let the baby experience some suck-sess first!  Trying to tackle too much at
the same time just frustrates everyone.  All things work out w/ a tincture of
time!!

Good luck,
Diane DiSandro, BA, IBCLC
Audubon, PA--private practice