How to extend or expand a RAID 1+0 on DL380 G5 with P400

while I was trying to extend a RAID1+0 on a P400 in a DL380 G5
I shortly realized something is missing in the ACU.

The Extend Array Button was missing, after reading in detail
the manual to ACU I found this HP P400 Overview.

That finally means no Extend Array Button when the BBWC(Battery Backed Write Cache) option is faulty or missing.

HP Smart Array P410i

Here some technical details to the HP Smart Array P410i Controller mostly found in
HP’s midrange servers like ProLiant DL380 G7

HP Smart Array P410i Chipset: PM8011

IBM ServeRAID M5014 and M5015 uses Chipset: LSI SAS2108

Dell performance summery LSI2108 vs PM8011