Hi,
AMF does not allow to modify the SG's writable configuration attributes like 'saAmfSGNumPrefAssignedSUs','saAmfSGMaxActiveSIsperSU','saAmfSGMaxStandbySIsperSU' or in case of N+M SG 'saAmfSGNumPrefActiveSUs' and 'saAmfSGNumPrefStandbySUs'.
We need to lock the SG to modify any of its writable attributes.
It is documented in Amf PR Doc.