I don't believe that data is recorded in the part file or if it is, Siemens wants to keep it quiet.
You can get part history, which will show the username and workstation ID of all changes made to a file. From a session of NX, you can get the customer sold-to ID from the Help-About NX information window.
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli