How can i combine/merge some facet forms?

Thanks for reply Chris,
Unfortunately is sandbox project (Facet API Block), not solved the problem for me, because i need a single block and single form width two multiselects and one submit button
I tried make this an realm system, but didn't understand how work it.
custom_facet.module

function custom_facet_facetapi_realm_info() {
  $realms = array();

  $realm_info = module_invoke('facetapi', 'facetapi_realm_info');
  $realms['combo'] = array(
    'label' => t('Combo facets'),
    'weight' => -8,
    'default widget' => 'facetapi_multiselect',
    'element type' => 'form elements',
  ) + $realm_info['block'];

  return $realms;
}

function custom_facet_facetapi_facet_info_alter(array &$facet_info, array $searcher_info) {
  $facet_info['im_field_data_meter']['default widget'] = 'combo';
  $facet_info['itm_field_range']['default widget'] = 'combo';
}

function custom_facet_block_info() {
  return facetapi_get_block_info(array('combo'));
}

function custom_facet_block_view($delta = '') {
  return facetapi_block_view($delta);
}

And where my block "Combo facets"? What am I doing wrong?
Thanks,
Max