I have not, didn't even think about it.
Trying it now, I imagine it will still take a little bit to finish as the pool with those drives added is not small. Just really hope it works.
Thank you thank you thank you!!! It finished the remeasure way quicker than I would have thought and that works perfectly!!
Ok so to sum this up if anyone else wants to add drives with data into an existing pool and then include that data.
Stop DrivePool service - this avoids rebalancing while moving data.
Move (not copy) the folders/files you want in the pool to the hidden folder (Poolpart.XXXXXXX) on the newly added drive
Restart the DrivePool service
Files/folders will now show up in the drivepool
Run re-measure to get the drives to show space as part of the pool and not other
All done and significantly faster than copying terabytes of data