Kumar,
This is a little clearer, and the second part of my post applies. There is an OLE method to do this. I've copied some of the Macro help file example below. I'm not an expert with modifying catalogs this way, but it looks like you could create a loop to handle such a change for all classes assuming there is a relationship between the class name and the filter values for the table and column to be filtered. See the help files for futher information.
Regards,
Dave Griffin
Sub Main()
Dim objImpApp As Object
Dim objImpCat As Object
Dim objDB as object
Dim objUser As Object
Dim objFilter As Object
Set objImpApp = CreateObject("CognosImpromptu.Application"

Set objImpCat = objImpApp.ActiveCatalog
Set objDB = objImpCat.Databases("OUTDOORS"

Set objUser = objImpCat.ActiveUserClass.UserClasses(1)
Set objFilter = objUser.CreateFilterFor _
(objDB.Tables("COUNTRY"

.Columns("COUNTRY"

)
With objFilter
.AppendEx objDB.Tables("COUNTRY"

.Columns("COUNTRY"

.AppendEx 29 '<>
.AppendEx 1, "CAN" 'string constant
.Commit
End With
ObjImpCat.Save
Set objDB = Nothing
Set objUser = Nothing
Set objFilter = Nothing
Set objImpCat = Nothing
Set objImpApp = Nothing
End Sub
The Decision Support Group
Reporting Consulting with Cognos BI Tools
"Magic with Data"