How to use Supplier site details as condition in Redwood page rules on VB?

Summary:

Redwood Edit Pages: A DFF 'A' has been created on Self Service Procurement page. The field must be mandatory only when the Supplier Site Type (which is a DFF on the Supplier page). However, conditions such as Supplier Site, Currency are available, not DFF Type. How to bring the DFF as a condition?

Content (please ensure you mask any confidential information):

A DFF “A” has been created on the Self Service Procurement page as part of PR line. During the creation of a Purchase Requisition line, the Supplier and Supplier Site are selected.

While editing the page in Visual Builder, we would like to make DFF “A” mandatory based on the selected Supplier Site “Type.” This is another DFF configured in the Supplier's site page. However, the “Type” field is neither visible on the PR page nor available as a parameter within the Business Rule conditions.