“This is an unheard of situation. I have never heard of a case where a non-profit organization has been left to negotiate the terms of a proffer made by a developer to the City of Falls Church.” So Laura Hull, the executive director of a non-profit arts organization, told a work session of the Falls Church City Council Monday. Hull’s Creative Cauldron youth arts organization is working with the Falls Church Arts, Inc., to develop, utilize and operate 3,000 square feet of space set aside for the arts in the Pearson Square development now under construction on S. Maple St. But the groups could use some help, she intoned.