Mass Invoice allows you to create multiple invoices at once for each individual group - a real time saver. Add multiple different groups to one invoice, or create separate invoices for each group.
In the Bookings tab, select each booking you're creating an invoice for, then click +Mass Invoice in top right hand corner drop down menu.
A pop up will show up allowing you to make any notes or changes to what you've selected, once finished click Create Invoices.