How to configure BU's for External Purchase Prices Requisitioning BU Mapping

Summary:

For task External Purchase Prices Requisitioning BU Mapping

I am only able to select the BU that is the Procurement BU as the Requisitioning BU, i need to be able to select multiple BU's as Requisitioning BU's. What setup am i missing?

Content (please ensure you mask any confidential information):

Content Release: 23BD01

Version (include the version you are using, if applicable):

24A

Code Snippet (add any code snippets that support your topic, if applicable):