--- lib/HTML/FormFu/Model/DBIC.pm	2009-05-28 18:24:29.000000000 +0200
+++ lib/HTML/FormFu/Model/DBIC.pm.new	2009-05-28 18:34:40.000000000 +0200
@@ -883,12 +883,13 @@
             my @values = $form->param_list($nested_name);
             my @rows;
 
-            if (@values) {
                 my $config = _compatible_config($field);
 
                 my ($pk) = $config->{default_column}
                     || $related->result_source->primary_columns;
 
+            if (@values) {
+                
                 $pk = "me.$pk" unless $pk =~ /\./;
 
                 @rows = $related->result_source->resultset->search( {
@@ -896,9 +897,25 @@
                         $pk => { -in => \@values } } )->all;
             }
 
+            if($config->{additive}) {
+                
+                my $relinfo = $dbic->result_source->relationship_info($name);
+                use Data::Dumper; warn Dumper $relinfo;
+                
+                $pk =~ s/^.*\.//;
+                
+                my $set_method = "add_to_$name";
+                my $remove_method = "remove_from_$name";
+                                
+                foreach my $row ( @rows ) {
+                    $dbic->$remove_method($row);
+                    $dbic->$set_method($row, $config->{link_values});
+                }
+            } else {
             my $set_method = "set_$name";
 
-            $dbic->$set_method( \@rows );
+                $dbic->$set_method( \@rows, $config->{link_values} );
+            }
         }
     }
 }
@@ -1396,6 +1413,34 @@
           model_config:
             default_column: foo
 
+If you want to set columns on the link table you can do so if you add a 
+C<link_values> attribute to C<model_config>:
+
+    ---
+    element:
+        - type: Checkboxgroup
+          name: authors
+          model_config:
+            link_values:
+              foo: bar
+
+
+The default implementation will first remove all related objects and set the
+new ones (see L<http://search.cpan.org/perldoc?DBIx::Class::Relationship::Base#set_$rel>).
+If you want to add the selected objects to the current set of objects
+set C<additive> in the C<model_config>.
+
+    ---
+    element:
+        - type: Checkboxgroup
+          name: authors
+          model_config:
+            additive: 1
+            options_from_model: 0
+
+(<options_from_model> is set to C<0> because this L</options_from_model> will try to fetch
+all objects from the result class C<Authors> if C<model_config> is specified
+without a C<resultset> attribute.)
 
 =head1 COMMON ARGUMENTS
 
--- t/update/many_to_many_select.t	2009-05-26 21:10:21.000000000 +0200
+++ t/update/many_to_many_select.t.bak	2009-05-28 18:37:01.000000000 +0200
@@ -1,6 +1,6 @@
 use strict;
 use warnings;
-use Test::More tests => 5;
+use Test::More tests => 14;
 
 use HTML::FormFu;
 use lib 't/lib';
@@ -39,6 +39,9 @@
     # band 3 - not used
     $schema->resultset('Band')->create({ band => 'the kinks' });
     
+    # band 4 - not used
+    $schema->resultset('Band')->create({ band => 'the hoorays' });
+    
     # band 1
     $u2->add_to_bands($band1);
 }
@@ -75,3 +78,73 @@
     is( $id[1], 3 );
 }
 
+# additive and link_value
+
+$form = HTML::FormFu->new;
+
+$form->load_config_file('t/update/many_to_many_select_additive.yml');
+
+$form->stash->{schema} = $schema;
+
+{
+    $form->process( {
+            id    => 2,
+            name  => 'Paul McCartney',
+            bands => 2,
+        } );
+
+    ok( $form->submitted_and_valid );
+
+    my $row = $schema->resultset('User')->find(2);
+
+    $form->model->update($row);
+}
+
+{
+    my $row = $schema->resultset('User')->find(2);
+    
+    is( $row->name, 'Paul McCartney' );
+
+    my @bands = $row->bands->all;
+
+    is( scalar @bands, 3 );
+
+    my @id = sort map { $_->id } @bands;
+
+    is_deeply( \@id, [qw(1 2 3)] );
+}
+
+{
+    $form->get_field('bands')->model_config->{link_values} = {rating => 200};
+    
+    $form->process( {
+            id    => 2,
+            name  => 'Paul McCartney',
+            bands => [qw(1 2 3 4)],
+        } );
+
+    ok( $form->submitted_and_valid );
+
+    my $row = $schema->resultset('User')->find(2);
+
+    $form->model->update($row);
+}
+
+{
+    my $row = $schema->resultset('User')->find(2);
+    
+    is( $row->name, 'Paul McCartney' );
+
+    my @bands = $row->bands->all;
+
+    is( scalar @bands, 4 );
+
+    my @id = sort map { $_->id } @bands;
+
+    is_deeply( \@id, [qw(1 2 3 4)] );
+    
+    my @link = map { $_->rating } $row->user_bands->all;
+    
+    is_deeply( \@link, [qw(200 200 200 200)] );
+        
+}
\ No newline at end of file