Jan,
Rinsing the beans may help.  Read somewhere long ago that pentose sugars in
beans caused the gas.  unsure of whether or not this would get into the
breastmilk and cause gas.  soaking and rinsing the beans before cooking/eating
is supposed to reduce the sugars and gas.
        another possibility to look at is the moms use of soy products.  soy
allergies are common in infants, and vegans often use lots of soy- soymilk,
tofu, textured vegetable protein, soy flour, soybeans - you get the drift.
        then of course there is the management course: increasing hindmilk
intake by nursing longer at each breast.
Let us know what works.
Catherine Watson Genna, IBCLC  NYC   [log in to unmask]