A. During the pendency of a proceeding, changes and modifications may be made by the board in the acquisitions or improvements, the cost estimate, the diagram, the boundaries of the assessment district, the extent or apportionment of the assessments, or in the proceedings.
B. Unless requested by such owner in writing, no change or modification shall be made except after hearing on notice by mail, at least ten days prior to the hearing, as provided in section 48 981, subsection G, to:
1. An owner of real property in an area proposed to be added to the district.
2. An owner whose assessment would be increased.
3. An owner whose assessment would be changed by more than ten per cent by reason of changes in the acquisitions and improvements. 48987