The main record has a Student ID and each student in the portal has a StudentID, so you can set up a conditional format on the portal row fields that when:
StudentID = studentID_selfByWhateverYouJoinBy::StudentID
then the fill colour is yellow, say.
Your technique works, but its not quite what I need.
I should have expressed myself better in the original question.
What I need is a method to ensure that when I move to a record in the Main table the Portal records are in sync with the Main table.
So when I press the < Prev and Next > buttons on the toolbar, the same record is visible in both the Main and the Portal.
I hope that makes sense.
I have worked on this a bit, (hours!), and I have botched a solution. I have put two buttons with scripts on the layout that move to the <Prev and Next> record in the Main and the Portal at the same time. It works, but its not pretty.
However, it will do for now, and I learnt a bit more about scripts in the process.
What is the relationship that you use for the portal? What fields match and with what operator?
What you describe should take place automatically, but the portal may need to be scrolled to the matching record in the portal to make it visible.