I have a expression to define the XSD for my XML source as I don't want that file path to be hardcoded. I have it set in the Control Flow Data task event - clicked on Expressions and selected XMLSchemaDefinition - there I have it set to a variable. In the Data flow - XML Source Event, I have the location set to a variable and the XSD location is hardcoded. Is that correct? even though it is hardcoded, does it use the expression variable location, overriding the value that is set in the XML Source definition? thanks

Just Give a wrong path in hardcoded area and TEST. If it fails, Its is not using variable's path.

The answer for your question is YES, It will use variable if it was defined and SET correctly.