just add a condition based on either the value of a variable (button) or the output of Getfieldselections() (inline listbox for selection) to any dimension or expression that you want to use in the graph. There is an edit_field for each in the dialog.
That way, you can use that listbox or button to change which dimension(s) or expression(s) your graph uses.
You can create a variable with button action to change between 0 and 1 (If(vVar = 0, 1, 0)). The way the if statement is structured the value of vVar will swap between 0 and 1. So now you can use expression condition for your set of expressions like this vVar = 0 and vVar = 1. If you need more sets you can do like this(If(vVar = 0, 1, If(vVar = 1, 2, 0))).
I hope this will help.