If you are trying to pay multiple invoices from a vendor, Melio won't let you do it with a single payment yet. In order to cut a check for multiple invoices, you need to enter them as "bills" not expenses. Then you can pay multiple ones at once.  Open an unpaid invoice and click "mark as paid."  All of your open invoices from that vendor are there.  Check the box for the ones you want to pay.  QBO automatically adds them up.  Then at the bottom click print check. You can do this even if you are not actually paying with a check, but are paying online.