Add a concept of petition attributes to be completed by the approver, rather than the petitioner. (This could also extend to other classes of people). For example, the approver might be the one to select the affiliation of the enrollee.
This gets a little complicated in that createPetition() can't complete until all the attributes are provided. Some refactoring might be needed.
Also, "required" attributes will need to be flagged to apply as "required for petitioner" vs "required for approver", etc.