How to create style under genre

is it possible to create style under genre, like in Discogs.

Current this what i have

jazz//vocals//Soul
Jazz//instrumental
Rock//Soul
Rock//Pop
Blues
Blues//Ragtime.

The list goes o and on...
but it has gotten to long for the drop down menu in MP3tag.

Would like to change like thia

Jazz
Jazz//Fusion as a separate field under jazz

Rock
Then Classic Rock
Hard Rock

Is this possible?

Thaks

No. You cannot define any dependencies between fields.
Also see