I used .omf for export on that occasion, using rough audio mixdowns for musos to work to from C4 into C5, then .omf taking new audio performances back to C4.
MIDI files can be imported and exported freely of course, so although it’s not ideal, it’s workable. I didn’t even bother to set the C5 tempo - everything landed back in the right place. If in doubt a click or a count-in ahead of the rough backtracks, copied ahead of the new material before making the .omf can be matched when you’re back at home.
Study the .omf window before committing, you can set the files you want to include from the list on the left.
Set locator limits if you wish
Set file destination path
Tick ‘Copy media’
Set Export to one file
The other options are detail tweaks
…and you’ll end up with a single large file that you can easily import to your original project using the .omf import dialog (last option on File>Import
Works for me!