- Shift-Right mouse button (Probably too easy to mis-click, but neatly combines "Right click to mine/remove" with "Shift to force blueprint placement")
- Ctrl-Shift-Click (Uses an extra modifier key for safety, while still being convenient)
The behavior is effectively a spatially-filtered deconstruction planner, marking old structures for replacement if they block the new blueprint while ignoring things that can stay.
This would enable vanilla Upgrade Planner (though not Builder) behavior if combined with a UI that upgrades the blueprints themselves (like Autotorio's Upgrade Blueprint option).
Aside: Currently in the hotkey menu "Build ghost" is the English label for the "Shift-Left mouse button" hotkey responsible for placing an entity as a ghost, which makes sense, but leaves out the "Force Blueprint Placement" and "Ignore Trees/Rocks" behaviors. Discoverability might benefit from additional description here.