Source File column was introduced with AMA which I believe came in a later version than 3.5. I am trying to remember how an in import is tracked in that version in order to enable a “merge”.
What I used to do in earlier versions, is first import the ALE, then do a “batch import” into the master clips created by the ALE file. But… unless the ALE reflects EXACTLY the START, END and DURATION, the import process will add or remove frames resulting in a wrong representation of the assets.
In your scenario, import the assets, and see what column are populated. One of then should be the file name. If it is not TAPE or SOURCE FILE, you will not be able to merge.
Michael