Hi Katherine, You can certainly add it, however typically in an ITIL world, only the analyst would set that, and not the end users. Impact is something used by analysts to take into account things like how many users or organizations are affected etc. This is used as part of the "priority calculation" - which is based on the impact and urgency fields. The urgency would be filled in by the end user, and the impact by the analyst, which together would then calculate the priority value. You can certainly add the field to the employee detail_in.htmpl and detail_cr.htmpl forms using Web Screen Painter. You would also have to set function access to "view" for them on the impact object so they can see it as well.
Hope this helps
Jon I.