We tested the suggested approach but eventually decided that we would try a non-technological solution to the problem.
Teachers were thinking quite linearly and trying to make each Moodle topic equal one week in their college course. So now we're persuading teachers to structure information in their Moodle courses differently, so that each Moodle topic equals a unit in the college course. They're learning to create web pages within a topic to store any further information that needs to be displayed or using directory links to show fodlers full of relevant files.
I still believe that there is a real need for a Master Course/Child Course relationship within Moodle. I'd try to create it myself but my programming skills are not up to the task - maybe when I can wrangle some free time from one of our IT programmers. If anybody else wants to have a go you'd find a happy VLE admin here...