Hi Maarten

It is possible to enrol audience members in programs or course - it is the limiting of users and pririotising that isn't possible using dynamic rules.

One way around this is to create a user profile field that an admin can tick if they want the user in city 'Z' to be enrolled.

The first rule would be to select users who are in city X or Y - the second rule would use an OR and include a rule for users in City "Z" and the profile field checked.  The manager would tick this fieldafter looking at the users who are already enrolled in the course through the first rule the user would be included in the Audience.

The course or program completion report could be created to list users who have the city Z in a specific course and their checkbox value.

Let me know if you have any questions on this suggestion.

Regards