CoPerson has various dependent = true relations to CoPetition. This isn't right, as deleting a Petitioner or Sponsor would delete any petition they created or sponsored.

Approver/Petitioner/Sponsor should not have dependent=true. Instead, delete CO Person should throw an error and expunge should special case, sort of like for notifications, probably by unsetting the foreign key and adding a note to the petition history ("Sponsor Jane Doe expunged").