Upgrade drive without reformatting?

Hi, I have a G-RAID USB Removable 8TB in RAID 1 mode (so 2x4TB drives) that I want to upgrade to 6 or maybe even 8TB drives. Two questions:

  1. I see that there are specific drives that I would need for this system? Where can I find which model numbers are supported?
  2. can I do an in-place upgrade? ie: can I pull out one drive, put in the larger one, let it sync, then do the same for the other drive and then simply expand the disk in Windows Disk Management? Or do I have to yank both out, put in the new ones, redo as RAID 1, reformat, and use one of the old disks to copy the data back? (I have a spare external USB 3.0 shell)
  1. You can technically use any 2 drives that share the same model #s we just haven’t tested anything beyond the HGST Ultrastar drives.

  2. You will need to replace both drives at once. You’ll need to transfer the data elsewhere, put new drives in the enclosure and create the RAID1. Then transfer the data to the new drives.