Field observations in Appraisal Document HAP_PDF_OFFLINE_FORM

Dear experts.

I have the following doubt:

In the appraisal document is requiered that the appraiser can add more observations fields(field inclosed in the box red), our requirement is that exist a button "Add" for put more observations and to get and history of the observations.

How can do this?

I am using the option:

• Note Can No Longer Be Changed
  Every participant can read, but not change, a note written by another participant. A field for entering a note is available for every participant.

Using this option the system allow change the commentaries created by the appraiser in the same status  and not allow modify the comment when the  status of the appraisal document changes.

Thanks in advance

Regards