You can do something like this: (only kinda tested and probably not exactly what you wanted, but at least the output matches what you wanted)

if (open(FH, "<yourdatafile.txt"))
{
  while (my $line = <FH>)
  {
    my @columns = split(/\|/, $line);
    my $stage = 0;
    my $prefix;
    my @sections;
    my $sectionIndex = 0;
    foreach my $column (@columns)
    {
      next if ($column =~ m/^\s*$/);
      if ($column eq 'Q')
      {
        $stage++;
        next;
      }
      elsif ($column eq 'S')
      {
        $stage++;
        $sectionIndex++;
        next;
      }
      elsif ($stage == 0)
      {
        $prefix = ($prefix ? join('|', $prefix, $column) : $column);
      }
      else
      {
        $sections[$sectionIndex] = ($sections[$sectionIndex] ? join('|
+', $sections[$sectionIndex], $column) : $column);
        $sectionIndex++ if ($stage == 2);
      }
    }
    foreach my $section (@sections)
    {
      $section = join('|', $prefix, $section);
    }
    print join(' ', @sections)."\n";
  }
  close(FH);
}
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Your question wasn't very easy to interpret. If you can clarify what you want, it would help answer your question.