Custom Field Populator: How to Add Custom Fields to Existing Items
You can add custom fields to items quickly using Custom Field Populator. First, make sure you have created the custom field you want to add.
Step 1: Go to the Dashboard and click on Custom Fields:
Step 2: Click the Edit tool to edit the custom field.
Step 3: Toggle Add this custom field in ALL products in BigCommerce? to Yes and click Save Custom Field.
Custom Field Populator will then add the custom field to all existing items in your store.