The /myfolder/my.cnf file has option set: [mysqld]
skip-log-bin
/myfolder2/my.cnf has this option set:
[mysqld] log-bin = /valid/path/to/mysqlbinlog
All mentioned paths are accessible to the account that you are currently using.
Assume that any other options mentioned in either file are valid and legal option definitions.
You start an instance by using this command line: mysqld --defaults-file=/myfolder/my.cnf --defaults-extra-file=/myfolder2/my.cnf What is the outcome?