How do I get billable expenses to appear at the bottom of the invoice as a group rather than appear by the date which they were entered ?

You will be able to place billable expense with subtotal after product/service items. Since billable expenses were entered as a separate item, there is no group all those billable expenses and show as one item.

In order to do that, you will need to customize invoice format.

Open Invoice form, click customize button at the bottom

Select “More” tab

Select “Group Activity” by “Type” checkbox

Also select “Subtotal groups” checkbox

Save