I use this work around in QBO. From the Customer transaction list, select the invoices you want to send. Using the BATCH ACTIONS button select Print Transactions. When the print window pops up choose Print to PDF, and save the multiple invoices as a single PDF. You can then email the PDF as an attachment.
This doesn't allow for payment from within the invoices themselves like sending them individually does, but it keeps your customer from receiving so many emails for multiple invoices.
Hope that helps until QBO gets this worked out.