Edit labels for Poly recorded audio

I'm working on a project where we record audio in poly, which gives us one file with up to 4 track's of dialogue. When importing these files, FCP automatically assigns track 1 as Tr1, up to track 4 as Tr4 (see screenshot). But if I want to edit these roles with character names, FCP only allows me to give it one audio role. 

Is there a possibility to assign multiple audio roles myself? 


Note: I did try to change the role name in the timeline with subroles on, but in this view all the audio roles are greyed out, and I can't change them.

In the audio editor you can assign a different role to every track. Set it to 4 mono first.