Can I do progressive upgrade of disks in MyBook Duo

WD External and Portable SSD External SSD for macOS
1

I have 2 x 2T disks mirrored. I was hoping I could
break the mirror
upgrade disk1 to a larger disk
copy the data from disk2 to disk1
upgrade disk2 to a larger disk
re-mirror from disk1

Big ask, I know, but it seems like any change I make deletes all the data.

2

Perhaps it would be best to contact WD Support about this. You can do so over the phone or via E-mail.