Hello! 

Since I do not have a event.tsv file, I tried to format my txt files into a csv file. 

The problem I had before with my onset files being added as a condition of its own seems to be fixed after changing the headers as 

[ condition_name, subject_number, session_number, onsets, durations ]

So far, I was able to import files for multiple subjects with multiple sessions with this format. 

I hope this helps! 

cheers,
syoun