I don’t know if the WD Sync program will recognize/remember the folder on a USB drive if that drive is removed and remounted at a later time. Only thing I can suggest is to give it a try and let us know what happens.
On the question of bi-directional syncing with the WD Sync program. Some have reported that it does not sync in both directions for them. However when I setup the WD Sync software to test the software, it did do bidirectional syncing for me. You can read a bit more on the bidirectional syncing in the following thread including my post in that thread about bidirectional syncing with WD My Cloud working for me.
