Make Dependent Picklist Screen Components Required
You can now require user input for dependent picklist screen
components in flow screens. For example, if you have to capture both the make and model of a car,
you can now do it with a dependent picklist screen component, by making both picklists
required.
Where: This change applies to Lightning Experience and Salesforce Classic in Enterprise, Performance, Unlimited, and Developer editions. Dependent picklist screen components are supported only in Lightning runtime.
How: To make a picklist within a dependent picklist screen component required, set the Picklist 1 Required, Picklist 2 Required, or Picklist 3 Required attributes to {!$GlobalConstant.True}.