Close parent dialog box

In my Main dialog box (code below) there are two dynamic dropdown boxes. Values comes from static files.

Now when a value is not in the dropdownbox, there is a button next to it, that open a second dialog box. Where the user can insert the missing parameters.

I would like to close the first one from the second one, to have the data updated for the dropdown list.

Or is there a nother way to update the dropdown list ?

The main dialog box

--------- Show the dialogbox --------
	LrFunctionContext.callWithContext ("CreateDir", function (context)
		local f = LrView.osFactory ()
		local properties = LrBinding.makePropertyTable (context)

Code to close the main dialogbox 

LrDialogs.stopModalWithResult( CreateDir, "cancel" )