Moving symbols between schematic sheets: how to prevent breaking of PCB layout upon next update?

[eelik]

This FAQ article is still valid:

Update PCB from Schematic's match methods

Because this topic raises problems and questions perennially, here is another explanation which goes into more details. KiCad version 5.99 (pre-6.0, which is essentially similar to at least up to version 9) is used for reference. In KiCad changes made in the schematic must be propagated to the layout explicitly with Tools → Update PCB from Schematic. Notably KiCad must have some way to keep the connections between symbols and the corresponding footprints. Normally it’s done using internal uniq…

I very much agree with paulvdh, this really an important deficiency in KiCad. There even exists a worse situation (which was discussed here within a month or so): you can’t flatten a hierarchy by moving contents of subsheets to upper level in any practically feasible way if the design is complex/large.