Fixed number of Detail Lines

I have to create a report that will always show 12 detail lines per group, no matter how many records are in the group. For example, if there are only 8 records in the group I need to print 4 blank detail lines. I have it printing and breaking on the group just fine. How Do I get it to force the needed blank lines?
There will never be more than 12 per group.
I already have the report doing the new page on new group.
At this point the report works other than filling in missing detail with blank lines.
The report is a class roster which shows the students that have signed up for the class in a grid type layout. I just need the extra blank detail lines as a nice formating step. Some classes only have 4-5 students some have a full enrollment of 12Place a formula in the group footer to print 'n' blank lines.
e.g.

whileprintingrecords;
local numbervar lines := 12 - count({table.field}, {table.group});
local stringvar text;

while lines > 0 do
(
lines := lines - 1;
text := text & chr(13); //you may need chr(10) too / instead.
);

text

Tick the 'Can Grow' property of the object (right click, format field, common tab) and use the section expert to make the footer 'Suppress Blank Section'.