Moving folders · Moving specific folders
Can I keep editing files after they've been moved to the fast drive?
Short answer: Yes. Open and edit them as usual — the link leads to the file on the fast drive and changes save there. New files you add stay on your Mac unless auto-sync is on for that folder. The drive just needs to be connected.
Yes. Open and edit them exactly as before — the link at the original place leads to the file on the fast drive, so changes are saved there. New files you add to a moved folder stay on your Mac unless auto-sync is on for that folder, in which case they follow it to the drive.
The only requirement is that the drive is connected while you work. See auto-sync in What's Using Space.