Run second dialog after the first dialog is closedOK

I have a RunBase class, that has dialog with its own logic. My task is to add the second dialog according to condition (if Table1.RefValue == Table2.Value) after the first one is closedOk. The user insists of using the same button in form and not creating the new one. Should I create a new RunBase class for second dialog and pass the parameters to it(if it is possible - how to do it)? Or can I add extra methods to the existing class? But in that case there would be two run methods.
I’d be grateful for any suggestions and examples.

It sounds like you want to merely modify the GUI for getting parameters and not having two separate business processes, therefore you need just one RunBase class, not two.
The logic related to the dialog is called from in prompt() method, therefore you should put your logic somewhere there.
Details depends on what exactly you want to achieve. Consider overriding promptComplete(), for example.