Repeat to Repeat ( Many to Many ) Record Relationship

// Set repeat group id for select list
var repeat_group_id = 'aac1-614e-03e2'
// Set field id from repeat that will be used as select value
var repeat_group_field_for_select_options = '1a4e-a5e3-b2de'
// Set select field for related repeat selection
var related_repeat_group_select_list_id = 'cebe-a85b-7ef3';

// Create options on page load
create_related_repeat_group_select_list_options( {} );
// Listen to repeat group changes
formyoula.form_fields[ repeat_group_id ].on( 'element:create:success', function( event, data ) {
  // Create options on page load
  create_related_repeat_group_select_list_options( {} );
} );

// Main function to create select options for relating repeat groups
function create_related_repeat_group_select_list_options( options ) {
  // Get repeat group 
  var repeat_value = window.formyoula.form_fields[ repeat_group_id ].get('repeat_value');
  // Set select options
  var select_options = [];
  // Set select option values
  var select_option_values = [];
  // Loop over repeat group entries
  _.each( repeat_value, function( repeat_entry ) {
    // Loop over repeat entry fields
    _.each( repeat_entry, function( entry_field ) {
      // Check field id for select options
      if ( entry_field.component_id == repeat_group_field_for_select_options ) {
        // Push values for select field for related repeat selection
        select_options.push( entry_field.value );
        // Push repeat entry id for workflow mapping
        select_option_values.push( entry_field.attributes.repeat_entry_id );
      }
    } );
  } );
  // Update select list with new options
  window.formyoula.form_fields[ related_repeat_group_select_list_id ].set( {
    select_options: select_options.join( '\n' )
  } );
}