Drive Expansion (4x 2TB to 4x 4TB)

I have an EX4100 with 4x 2 TB WD Red drives in a RAID-5, which I’m replacing with 4 TB WD Red drives. I’ve swapped the disks one-by-one until the RAID was rebuilt. However, the system still shows Volume_1 as 6 TB usable space (instead of 12 TB). How would I go about expanding “Volume_1” to utilize the full 16 TB of new space (without losing my data)?

PS: Currently running firmware: 2.30.165


I have never tried this.
I recommend you contact WD support for assistance.