Entering and synchronizing Xero Bills feature is available from Version 11.5 and onwards.
A new record type “Xero Bill” is introduced on the Xero Invoice/Credit Note (AAkPay__Invoice__c) object. In order to create a bill record, select this record type and fill the other details similar to Xero Invoice.
Once all details are populated then mark this record for syncing to Xero again similar to Xero Invoices. Lastly, sync these records to Xero, the sync processor will create Bill To records in Xero because of their record type. For syncing these records to Xero follow the process similar to Xero Invoices.