1. Click “Combine” button, Combine page will open and show opened order on left pane.
2. Select target order, the order detail will be showing on right pane.
3. Click “DONE” button if you want to combine target order with current order. On order page,
ordered items of target order will be combined with current order by appending on order item
list.
4. Click “CANCEL” button if you don’t want to combine order.