Relationship for Work based on traditional

“all Compositions by Mosa Sisic except 2., 4., 5., 8., 9.: based on traditionals”

Now i’m looking for relationships for 2, 4 ,5, 8 and 9. They obviously have new titles and are supposedly very different to the originals, so probably not written by traditional. They are based on unknown works written by traditional.
The only thing i can think of is “arranger”.

“all Arrangements by Mosa Sisic & Harri Stojka”

… but i have used these as recording relationships for all tracks. And it’s probably not meant as work arrangement.
I have added [SubOptimalCredits] on work level, but apart from the recordings there are no relationships. Any ideas?

See: In Between