Part_Structure Tab customization

1. Our Windchill version is 12 CPS 17 using PDMLink/ProjectLink etc. Our industry is Aerospace and my role is a Windchill developer

My objective here is below.

In Part Structure tab, user could select the list of child and navigate to Viewing panel --> Show --> Documents, only displays the Describe document & Reference document.
We would like to show the Secondary Described By document as well.

Adding to this, Would be great if we can segregate the actions from Viewing panel --> Show --> (Instead of Documents), add Describe Doc, Secondary Describe doc & Reference doc, so that user can choose the required type and displays doc in the structure