A custom field can be added using the checkout page customizer so that the same info will be tracked under the customer's subscription section but it will not be displayed for now on the invoice. As our team is checking on the possibilities for the same, therefore notification will be shared accordingly if such an option gets implemented in the application.
Meanwhile to add the custom field via checkout page please follow the screenshot below for reference -
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For more info, please check this video tutorial on Checkout customizer in Pabbly Subscription Billing -
