Can I put an uplift on a whole chapter instead of every line?

When a handling or production uplift belongs to a whole department, add one Cost Item outside the chapter and point its Fee at the chapter's total by typing @. One visible line carries the uplift for the whole department, and it follows the chapter as the chapter changes.

An AddOn belongs to one Cost Item, which is what lets a duplicated line carry its AddOns with it. For a department-wide uplift you have two routes, and the choice depends on whether the client should see the uplift as one figure or as part of each position.

Option A: one uplift line

Add a Cost Item outside the chapter, for instance in a small chapter of its own, and name it for the uplift.
Click into its Fee and type @. The field's placeholder reads Number or @.
In the menu that opens, choose the Sections tab and pick the chapter.
Set Amount and the day count to 1, and drag a percentage AddOn onto this line, or express the uplift directly in Fee.

For example, a chapter totalling 80,000 with a 5 percent uplift line: the line reads 80,000 in Fee, and the AddOn adds 4,000.

Keep that line outside the chapter it points at. Inside it, the line would be counting itself and show zero.

Option B: configure one line and duplicate it

If the uplift belongs to each position, put the AddOn on the first Cost Item, set its rate, then use Duplicate Selection (⌘D) for the rest. A duplicated Cost Item carries its AddOns with it, so one configured line rolls across the whole department. If the rate is a Variable, one edit later moves every line.

The whole budget

To uplift the entire budget, wrap everything in one top-level Section first and point the uplift line's Fee at that Section.

Good to know

The menu behind @ lists Variables, Cost Items and Sections.
Selecting a chapter's lines shows Sum of Selection in the Action Bar, which includes AddOns as one combined figure.
For a breakdown per AddOn, open the sidebar Sections tab and its Smart Subtotals sub-tab. The AddOns block lists one row per AddOn used, with its share of the budget total, across the whole budget.