How can I edit two or more Bills together?

Yes, you can and it is called mass editing. 
Follow these steps to mass edit more than two records together:

1. Click the Main Menu.
2. Go to the Inventory tab.
3. Select the Bills module.
4. In the List View, hover over a record.
5. Click the radio button for the records that you wish to edit.
6. Click the Edit icon on the toolbar.
7. In the Mass Editing window, enter the necessary details.
8. Click Save.

You will be able to edit the selected records together. To know more about Bills, click here.