How do I make "on behalf of" user proof?
This is how we solved this problem for a client that has teachers as their constituents who all belong to a School Board/District. We're using the autocomplete functionality that webform_civicrm module provides to force teachers to select rather than to type. You can only imagine how many ways one could type "Grande Prairie Roman Catholic Separate School Disctrict No. 28" before we locked this down...