Please follow the steps mentioned below to link an invoice to a subscription invoice:
Step 1: Go to Sales >> Invoices >> Click on 3 dots for the invoice that you want to link to a subscription invoice >> Click on Link to subscription:
Step 2: Select the Existing Subscription to which you are looking to link the invoice
Note: You can create a new subscription if there are no existing subscriptions available.
Step 3: Click on Link to Subscription
Please note:
1. To link an existing subscription invoice with a sales invoice, the customers and either one of the products added in the invoice and the subscription should be the same.
2. This feature is available only in the web version.