Tarun, I'm getting closer all the time to understanding your problem, but still not totally clear. Are you dealing with 2 different parts? What two dimensions are you comparing to determine your add/remove decision? I'm guessing you can use ordinary conditional Relations without Pro/PROGRAM to do what you want. However, here goes on how to do what we've discussed using Pro/PROGRAM. Select Tools/Program/EditDesign. Near the beginning of the default Program, between the lines "INPUT" and "ENDINPUT", enter the line REMOVE YES_NO. This declares a parameter named REMOVE for use in the program and establishes its type as YES_NO (the default is Real Number). Now locate your two features in the Program. Each will be a section of several lines containing all the details and values for the feature. Before the "Add Feature" line for your "Remove" feature, enter the line: IF REMOVE==YES, and after the "End Add" line enter: ENDIF. Before the "Add Feature" line for the "Add" feature, enter the line: IF REMOVE==NO, and again ENDIF after the "End Add" line. Save your program. Now if you change the value of REMOVE, and Regenerate, the model will change as you wish. Good luck! David