I did more research and saw that you can add a Volumes_2 with the extra space but only option seems to be as Spanning.
WD has no option to increase the drive partition size. I verified this with WD Tech Support. The only way to use the extra space is to redefine your RAID 10 which erases it and the only option is to restore all your file.
I was using 7.5TB so that takes a long time to restore!
There is software available to resize drive partitions and I assumed that WD would resize them after increasing the all the drives to larger drives.
I wasted two days installing each drive individually (Hot Swap) with the expectation that in the end there would be a way to automatically increase Volume_1 without a full restore,
Had I known that, I would have to re-initialized the RAID 10 to increase the size, I would not have wasted two days doing the How Swaps.
It would be pretty simple for them to increase the partition size without a restore, but I guess they are too lazy to do it, don’t want to pay a license fee to use someone else’s partitioning software or just want to sell more external drives.
Just seems like a big waste to time to not be able to increase the drive partition size on the fly and force you to have well over 24 hours of down time restoring your NAS!