Configurating a primary with two standbys ( DB_FILE_NAME_CONVERT, LOG_FILE_NAME_CONVERT)

I came across a problem configurating two parameters (DB_FILE_NAME_CONVERT  and LOG_FILE_NAME_CONVERT) in the primary database while I am building a primary database server  in preparing for two standbys to be built (on two separate boxes).  I was able to understand one primary with one standby configuration, but with two, I need a little help here and hope you could assist with these two parameters.

Here is the scenario of parameters used:

PRIMARY:                DB_NAME =ICMSTEST, DB_UNIUQE_NAME=M1

1st standby:             DB_NAME =ICMSTEST, DB_UNIUQE_NAME=M2

2nd standby:            DB_NAME =ICMSTEST, DB_UNIUQE_NAME=M3