For users already familiar with CommCare's conditional select functionality, referencing locations within a form is very similar. To access the list of locations from within a CommCare Supply form, you can use the syntax described HERE.
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If you don't see the 3 dots (), you need to activate a feature flag in your project settings.
Add your project space name to the feature flag 'Allows user to configure itemsets for more than lookup tables', here.the feature preview "Custom Single and Multiple Answer Questions" to your project