issue when opening a dialog on top of other

Summary:

Hi Experts

When I try to open a dialog on top other dialog i.e. on click of button I open a main dialog and on click on button I try to open a small dialog on top of previous with the help of action chain call component.

But the problem over here is when I try to open a dialog over another the main dialog overrides the smaller one, so in order to view the smaller dialog I have to close the main dialog which shouldn't be the case. Please help me how can I show the small dialog on top of main one.