How about this.
Add a number of Report Footers, with a text box in each to match the printed lines, ready to be written in. Then conditionally suppress these, depending on the number of extra students you have, which is your parameter. With a bit of ingenuity with the conditions, you could add up to 7 students with only 3 footers.
(1,2, & 4 rows)
You will need borders on the boxes, and a character in there (like a .)
because Crystal won't print borders on an empty box. But you can turn the text colour to white so it doesn't show.
I've had to make reports like that before, but not with a parameter.