FBAR report investment account with a common account number for all participants

Hi,

 

A family member of mine has money in several investment accounts abroad where each account has a common account number that's shared by all its participants. They work just like regular saving account where money can be deposited to collect interest except for not having a separate/unique account number for each individual. They may be similar to mutual fund or pooled fund in concept. How should these accounts be reported on FBAR? I'm thinking he should just report them as if they are individual accounts. However the same account number could be reported by many other people.

 

Thank you!