08-10-2021 11:38 AM - edited 08-10-2021 11:38 AM
First, make sure the UD1 combo box is set to refresh the dashboard:
Then, the UD2 combo box would need to reference a business rule, whereby you apply the logic to query the appropriate UD2 members based on the UD1 value.
Source: Office Hours 2020-12-17 Partner Enablement