The results of adding a field to an Item Type will not cause any adverse effects to the existing items. It will, instead, add a blank field to the Item Type.
Creating the FieldTo add a field to an Item Type you must be a Jama Admin. Select the
Item Types menu, then decide which Item Type will get a new field. Select
Config in the same row as the desired item.

A window will appear to the right showing
all available fields in that Item Type as well as options for editing the list of fields in the upper right. The icons are (from left to right)
edit,
move up,
move down,
delete and
add a field.

Add Field will open a dialog box where you can specify the details of the field.

First, decide if this will be a
Predefined Field or a
Custom Field. A
Field Label is required, as this is the field name that users will see. A
Unique Field Name will auto-populate in an editable field when a
Field Label is chosen. Once the field has been created and saved, the
Unique Field Name will no longer be editable in either the UI or with the API.
For additional information on adding fields, you can check out the Jama User Guide's entries on
configuring an item type and modifying fields.
Adding New Fields to the Review CenterWhen you have finished creating the field, you must make sure it is viewable in the Review Center by going to
Admin > Item Types, selecting
Configure View on the item in question, and using the drop-down menu to select
Review Center Single Item View and
Review Center Reading View. The
Review Center Reading View is the default view that displays multiple items per page, while the
Review Center Single Item View displays just one item in detail.

When you move the new field to the
Visible Columns you can go back to your review and see your newly-created fields.
The new field will appear in the Review Center without a new revision. When you fill the new fields in, you will have to publish a new revision in order to see the data. Publishing a new revision will let approvers and reviewers know that there is new information to review.