Hi:
Per the emails you sent me, it seems as if you have a few different data sources that would be used to provide options to the user in the drop down based on who the user is.
One option would be to have a number of drop down controls on your form, each bound to the same field, and each using different data sources for their items. Then use conditional formatting to display the correct drop down to the user. Don't query all your data sources on load, just query the one you need for the correct drop down in open rules or other rules (whatever the logic is to determine the correct drop down to show).
Another option would be to have an XML file as a secondary data connection, with no values in it, then using qRules or code, copy the correct items in from the correct data source.