SAC member FORMULA

In classic BPC we have member formula say for an account dimension ( example P_ACCOUNT )

and it has a member ( or masterdata ) = 1001. and COST_CENTER is another dimension with member CC100

and I have the formula [P_ACCOUNT].[1001] - ( [P_ACCOUNT , [COST_CENTER].[CC100])

how do we do this is SAC , I cant seem to cross P_ACCOUNT boundaries in SAC formula