Hello ddemocko,
Collaborator doesn't allow to automatically change the "Review Custom Field" visibility depending on the another "Review Custom Field" values. The visibility depends only on the review phase ("Visible Phase" option). If you don't have many cases, in which you need automatically change review custom fields, you can create templates for each case and change it during the review creation process. Please note changing templates in the review removes all participants and resets custom fields.
In addition, you can register a request in our special forum thread so that our R&D team could consider implementing the feature in the future.
There is also a capability where you can define "dependent fields". You create the custom field as a dropdown list, then define the titles and values with the pipe char in between: Domain|Subdomain|Component, and all the values need to have 3 values. If you don't have all 3 in some cases, fill with "none" or "na".
