Getting other project costs onto sales invoice

Good day all. Trust you are all healthy and well.

When I generate a sales invoice from the project-page, it shows the time-sheets that
has been booked against the project.

I still have to enter those time-sheet hours into the sales invoice via an item.
Thats fine.

It does however not show the other expenses - expense-claims and purchase-costs.

So for me to have it listed there ( even though I still have to enter those costs via an item),
I would have to customise the sales invoice on the client side? Correct.
And as long as I do it on the client side it will not disappear when I update?

Thank you