You can change the contents of a batch that has already been sent from Xero up until the time the batch is actioned in the app. To add a bill to a batch that has been sent to the app, set the Planned date of the bill in Xero to the same date as the batch. To remove a bill from a batch that has been sent to the app, change the Planned date of the bill in Xero to a later date or remove the Planned date for the bill.
Updated over a week ago