Official comment
Hello Anton,
In version 6, you will have to put the job inside a setup and schedule the setup for the second schedule. For example, Job A can be scheduled to run Mon-Sat at 4am, and then put Job A into a Setup, then schedule the setup for Sunday at 10am.
In version 7, we allow for multiple schedule trigger elements on a single job, which negates the need to put the job inside of another to schedule it.