PBS Permissions for creating a PBS only as a child

Feature Request: PBS Root Creation Permissions

Summary:
Introduce permissions that restrict certain users (e.g., BOE Authors) from creating root-level PBS elements, while still allowing them to add child levels under existing PBS structures. This ensures controlled PBS hierarchy management without blocking authors from extending the structure where appropriate.

Problem Statement:
Today, authors who can work with PBS may also be able to create new root-level PBS entries. This can lead to unintended proliferation of top-level structures, fragmentation of the PBS, and inconsistency with the agreed WBS/PBS design. In scenarios where a proposal’s PBS is predefined (e.g., aligned to WBS through level 3), authors should not be able to introduce new root or peer levels, but they still need to add deeper child levels (e.g., level 4 and below). The lack of granular permissions makes governance difficult and increases the risk of structural errors.

Proposed Solution:
Add configurable PBS permissions that distinguish between creating root-level PBS elements and creating child elements under an existing PBS node.
Allow administrators to define which roles or users can:

• Create root-level PBS entries.

• Create child PBS entries only under existing nodes.

• Modify or delete PBS nodes at specific levels (optional enhancement).
  When a user without root-level permission attempts to create a new PBS item at the root, the system should block the action and provide a clear message explaining that only child-level creation is allowed. For example, in a proposal where PBS (aligned to WBS) is defined through level 3, BOE Authors should only be able to add a level 4 under existing level 3 nodes, not create new level 3 roots.

Benefits:
Improves governance and consistency of PBS/WBS structures by preventing unauthorized root-level creation.
Reduces the risk of fragmented or incorrect top-level PBS hierarchies.
Allows authors to continue their work efficiently by adding necessary child levels without requiring admin intervention.
Aligns BOE authoring workflows with organizational standards and predefined proposal structures.