Combining project schematics

I have four separate KiCad projects, each with their own schematics hierarchy and PCB.

I need to now combine those four sets of schematics into a single schematic hierarchy (no PCB). In other words, the root sheet of the new schematic will have four subsheets, namely the root sheets of the other four projects.

Is this possible? All of the schematics use hierarchical labels on the root sheet and sub-sheets, so in theory I should be able to use the root sheets from the different projects as sub-sheets in a new project.

Normally the root sheet and sub-sheets (the .kicad_sch files) of a schematic are all maintained in the project folder. In my case I want to use the root sheets and sub-sheets contained in different project folders. Is that possible? And if so, how do I go about making that work, without any copying/pasting of schematics (that defeats the purpose—making changes to a schematic in one of my projects needs to propagate to the new project).

Thanks!

A hierarchical sheet in KiCad does not have to be in the same directory as the project. When creating a hierarchical sheet link, you can browse and select a filename from another project.

I do not have much experience with this though. KiCad does some wizardry to make it possible to include multiple instances of a hierarchical sheet in a project and I am not sure of the implementation for this. The KiCad manual does not have this detail.

But the KiCad manual does say:

Sheet files can be shared between multiple projects to allow design reuse between projects. However, this is not recommended due to path portability concerns and the risk of unintentionally changing other projects while editing a shared sheet.

So, as always, you should have a decent backup strategy in place.

Thanks for that, I’ll give it a try.

KiCad’s caution is because, with a sheet linked to two projects, any changes you make to the sheet would affect both projects. But that’s exactly what I want to happen, since one project is effectively the root of the others.