In Workfront Planning allow changing a Single-select field to Multi-select (and back) without recreating it

Description:

In Workfront Planning a custom field's type is locked once it's created. When a single-select field later needs to become "select all that apply," the only path is building a new field and this affects a lot of things: reports/views, filters, sorts, groupings, etc, and also Fusion scenario that might reference it. 

Proposed: in Workfront Planning allow conversion between Single-select and Multi-select (and back) in place, with guardrails:

• Compatible pairs only → other type changes stay blocked
• Values convert deterministically: "Option1" stays "Option1"
• Multi → single: keep the first value, pick a default, or block until conflicts are cleaned up, or just keep the same behavior as Workfront custom field have

Why it matters: this requests has hit us quite often from client, and its not because the field was wrong, but because requirements evolve