How blind SCG addition work in network?

5G NR
,
1

Hi All.

How blind SCG addition work in network?

Is key to use master? Seen in that case.

2

I think key to use has nothing to do with SCG addition method.

3

I seen key to use as master before SCG addition in RRC connection reconfiguration during LTE attach.

Once SCG addition there after B1 MR then key to use as secondary seen in RRC reconfiguration having NR cell config.

Is key to use mandatory IE or optional from network?

Any parameter there to control it?