I personally would create a third "access" doc type. It would have a link both a song and a user doc.
- Document design: Logging accesses to an item by a user Marian Steinbach
- Re: Document design: Logging accesses to an item by ... Mark Hahn
- Re: Document design: Logging accesses to an item by ... David Stuebe
- Re: Document design: Logging accesses to an item... Manokaran K
- Re: Document design: Logging accesses to an ... Dominic Tarr
- Re: Document design: Logging accesses to... Marian Steinbach
- Re: Document design: Logging access... Robert Newson