Dependent Concurrent Request parameter in a request set

Hi,

How can we depend the the default value of a parameter of a concurrent program to the previous parameter within a request set?

Below is the illustration of the setup:

We have a request set called Sample Request Set.

On the request set we have a concurrent programe called Sample Concurrent Program.

The concurrent program has parameter wihich is Param1 and Param2.  How can we assign a default value to param2 which will be dependent on the on the value of the Param1?

Thanks.