In your state, are child care centers required to be licensed?  If yes, you
might want to contact the state agency responsible for licensure.  It
sounds like they need to provide accurate information to the centers - on
cup v. bottle after 1 year, safety of breastmilk, etc.  Depending on how
they are regulated, they possibly could put out a statewide policy.  I
would also recommend the *no-spill cup* instead of a bottle.