Actually, I am just being dumb on a Friday afternoon?
The data sets all follow a naming convention so I can use wildcards in the window caption and map to "Settings for DataSet*" can't I?
While that won't uniquely identify the dialog on screen I can use some best practice in my script to make sure no more than one such dialog is visible at any one time. I don't need to compare the contents of "Settings for DataSet1" with "Settings for DataSet2" for example so one mapping with a wildcard in the window caption ought to give me what I need. I think.