Implements hook_form_FORM_ID_alter() for 'field_ui_field_instance_edit_form'.
function translation_entity_form_field_ui_field_instance_edit_form_alter(array &$form, array &$form_state, $form_id) {
if ($form['#field']['translatable']) {
module_load_include('inc', 'translation_entity', 'translation_entity.admin');
$element = translation_entity_field_sync_widget($form['#field'], $form['#instance']);
if ($element) {
$form['instance']['settings']['translation_sync'] = $element;
}
}
}