MD3200i virtual disk split

Hi,

I have MD3200i 10 TB

configured with 2 Disk Groups ( RAID 5, RAID 10 ) iSCSI (SAS)

in RAID 10 there's 4 virtual disks already created, I need to split an exist virtual disk to 2 virtual disks so the total in RAID 10 should be 5 virtual disks

please advice me how to do that

Regards;