If on the plugin settings page set 'Show terms childs' - all child terms on all taxonomies elements will be shown. To disallow it for multi-select this hook will help if return FALSE (by default is TRUE):
1 2 3 | add_filter('mdf_multy_select_show_all_childs', function($default) { return 0; }); |
From v.2.2.2/1.2.2