Hiding drop down values in Agentry complex table drop down

Hi;

I am working on a complex table drop down list (ctCodeGroup) on SMP 3.0 SP10 PL02. I have 4 values diplaying on this drop down and would like to only show 2 values instead of the 4 displayed values. How could I possibly achieve this?

Thanks and Regards;

Sizo Ndlovu