Full Drive swap

My Cloud OS 3 Personal & Network Attached Storage My Cloud EX4
1

I have a EX4 with 4 x 4TB and it is full. Would like to add 4 new drives and put the old drives on a shelf. Do I leave the device name the same with the new drives or do I make a new device name? If i need to put the old drives back in to get files will the box return to it’s “old self”?

TIA