use Pod::POM;

my $parser =  Pod::POM->new();
my $pom = $parser->parse_file(...);
my $h1 = $pom->add($parser, 'head1', 'This is a new head1');

##</code><code>##

my @SECTIONS = qw(name synopsis ...);

my $pom = $parser->parse_file(...);
my %found;
for my $h1 ($pom->head1()) { $found{lc($h1->title)} = $h1; }
for my $title (@SECTIONS) {
  my $h1;
  if ($h1 = $found{$title}) {
    print $h1;
  } else {
    print "=head1 ", uc($title), "\n\n";
  }
}