use XML::LibXML;

my $parser = XML::LibXML->new();
my $doc = $parser->parse_file("FILE1.xml");

my @nodes_from_file1 = $doc->findnodes('//Feature');

my $new = XML::LibXML::Document->new('1.0', 'utf-8');

my $features = $new->createElement( 'Features' );

#print to debug 
print $features->toString;

my $file1 = $new->createElement( 'File1' );

for my $node (@nodes_from_file1) {
    $file1->addChild( $node );
	
    #print to debug
    print $file1->toString;
	
}
$features->addChild( $file1 );

print $new->toString;
$new->toFile("output_new.xml")