Thank-you Derek for your reply.
It needs to be a hard limit unfortunately so we can't ask the user . I thought of creating an update job that goes and updates the max enrolment on each of the three courses as students enrol ie
300 is the limit set
A max = 300, B max = 300, c max = 300
5 students enrol in A then
A max = 295 B max = 295, c max = 295
BUT The downside is 900 students can enrol at once through bulk enrolment
I keep on wondering that maybe a two level meta course ( child- meta -meta) could help, but I can't think how
regards Paul