Thanks very much for your help. It's working fine!
I worked on some permutations/combinations to see what suited me best.
My final Code:
SELECT cname,classFROM biodata WHERE CNAME;
NOT in (SELECT cname FROM curselected);
AND biodata.gang=(lccontrol.combo1.Value)AND (DOL>=gdtodate OR EMPTY(DOL));
ORDERBY cname INTOCURSOR curtemp