| DirectX SDK | 
DirectPlay generates a DPMSG_ADDGROUPTOGROUP structure and sends it to every player when a group is added to a group.
typedef struct{
    DWORD    dwType;
    DPID     dpIdParentGroup;
    DPID     dpIdGroup;
} DPMSG_ADDGROUPTOGROUP, FAR *LPDPMSG_ADDGROUPTOGROUP;
  Windows NT/2000: Requires Windows 2000.
  Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Header: Declared in dplay.h.