By the way, at least in core BPC SP12 the following trick can be used to get a list of base members of some parent and then exclude some members:
*XDIM_MEMBERSET ACCOUNT AS %AC%=BAS(P_EA3700)
*SELECT(%AC1%,"[ID]",ACCOUNT,"[ID]=%AC% AND [ID]<>A_51800020 AND [ID]<>A_FCST_3700")
*XDIM_MEMBERSET ACCOUNT=%AC1%
Vadim