Hi, hema:
You can get the reference to every control in the cluster with the Cluster's CONTROLS[] property.
Controls[] is an array of References, in the same order of controls in the Cluster: the same order you enter controls. You can check/change that order selecting "Reorder Controls in Cluster..." from cluster's Pop-up menu.
Once you have access to every reference, you can use the Disable property.
I hope this helps you.
Aitor.
Aitortxo.