Yes, you will be able to bind a Fixed Virtual Account into an Invoice by using our Invoice API. Simply put Virtual Account ID in parameter callback_virtual_account_id in Invoice creation.
You may find out how to create a Fixed Virtual Account and Invoice on documentations below:
Fixed Virtual Account: https://developers.xendit.co/api-reference/#create-virtual-account
Invoice: https://developers.xendit.co/api-reference/#create-invoice