Carpet outputs its grid structure not in schedule groups, but instead in routines directly called e.g. from Initialise or Evolve. This would also simplify the patch. Could you add the call to output the grid structure to some location in Initialise.cc? Right after the call to "CallSetup" should be good.
Will do. It seems as if there already is the required code in Initialize.cc it's behind an "#if 0" though (and currently just before CallSetup). I'll see what happens if I activate that code. The code is commented out in the initial commit "Import Carpet".
I applied the change described above as hash 9ecc30e65127 "Carpet: output grid structures to file in Initialize instead of in SetupGH" of Carpet.