I've created a batch today for the payments that are due tomorrow, but they aren't available to add to the batch. How do I add them
For Regular Payments, the next Payment Txn will not be created until the date of the next payment due. So therefore only payments due today or before today will be available to add to a Direct Debit Batch.
Eg: Your client pays on the 16th of each month, the Payment Txn will be created when the Reoccurring Processor runs on the 16th. The Reoccurring Processor is set to run automatically at 1am each morning.