How to hide/show controls based on a condition

Hi all,

we have a business requirement where the customer is asking us for a help.

A small background:

There are several parties involved in the order process (Consignee, consignor etc...) and everyone of them needs to be picked on the order header.

What could happen is that for some of them we don't have any data to pick in Siebel and they don't want to really store those data in Siebel BUT they still need to put "something" as a value because they need to print a consignment note which is requested by law.

To implement this requirement System Integrator has customized the Order header form applet adding all the picklist fields they needed.