What your asking for can be done very easily. Within the library, add an extra field for Boolean and ensure 'list entry' is selected from the 'where can we edit' option. You'd be best adding this to the entry status in the field function (this is optional).
Now within your library list view you can select which tracks you want byticking the check box, when you've made your selections, access the context menu, filter and select the boolean checked option, this will now only display your checked tracks.
I'm not at my pc for a few days or I would provide some screenshots but hopefully you'll be able to understand my instructions.
I add my members once
I then add a new project for a member
Then ongoing I add notes as the project progresses. The project goes thru phases. Then, when I view a member I can see all the projects attached to that member. I can also see all the notes attached to a project when viewing a project.
Hope this helps. The point is you can see what songs you sang by creating a new project and then create notes for each project or gig.
I also do this to see what chores our family members have accomplished. I can view a chore of cleaning the kitchen. I can see which family member has cleaned the kitchen and when. I even assign points. I can view a chore and see all the history of which member has completed this chore historically. Or look at the family member to see what chores they have completed. Very flexible.