Enrolment

Here is the problem. We are getting our enrollment data from a database, however there are situations where we need to be able to manually add a student to a course without adding them to the database. The kicker is when the enrollment script runs, it removes anyone from courses if the database says they shouldn't be in the course. I would prefere that students not be able to enrol in courses buy clicking on them, which is what happens when internal enrollment methods are turned on.

The last thing I was wondering about was, is it possible to deney teachers from controlling enrollment in a course. This last part is is meaningless unless I can get the multiple enrollment problem fixed. Anyone have any ideas on this. I know its a strange problem but I would appriciate any help.