The SMP/E ZONEMERGE command will do this, It can copy one zone to another in the same CSI.
Syntax is:
SET BOUNDARY (DCOMMNT) .
ZONEMERGE(DCOMTGT ) INTO(DCOMMNT ) CONTENT DEFINITION REPLACE.
You then need to make a copy of the target datasets CABDLOAD and CABDMAC and rename the DDDEF entries in the new zone DCOMMNT.