How to simulate radio button functionality within a form
you should study the Ajax examples module you can follow the examples estructures to build you own code.
 After doing that your code should look somethink like this:

function test_code_radios_callback($form, $form_state) {
  return $form['radios_fieldset'];
}


function test_code_form($form, &amp;$form_state) {

    $options = array(
        'Name'=&gt;t('Name'),
        'Nickname'=&gt;t('Nickname'),
        'Lastname'=&gt;t('Lastname')
        );

    $form['alias'] = array(
    '#type' =&gt; 'radios',
    '#title' =&gt; 'Choose your alias',
    '#options' =&gt; $options,
    '#default_value' =&gt; isset($form_state['values']['alias']) ? $form_state['values']['alias'] : '',
    '#ajax' =&gt; array(
      'callback' =&gt; 'test_code_autotextfields_callback',
      'wrapper' =&gt; 'textfields',
      'effect' =&gt; 'fade',
        ),
  );

    $form['textfields'] = array(
    '#title' =&gt; t("Your Alias"),
    '#prefix' =&gt; '&lt;div id="textfields"&gt;',
    '#suffix' =&gt; '&lt;/div&gt;',
    '#type' =&gt; 'fieldset',
    '#description' =&gt; t('Write your alias here'),
  );


    if (!empty($form_state['values']['alias']) &amp;&amp; $form_state['values']['alias']) {
    $value = array();
    $value = $form_state['values']['alias'];

    foreach($value as $item) {
    $name = $item;
    }

      $form['textfields']['$value'] = array(
      '#type' =&gt; 'textfield',
      '#title' =&gt; $value,
      );

  }

  return $form;
}
function test_code_autotextfields_callback($form, $form_state) {
  return $form['textfields'];
}


I tested and it's working as i understood you need it. Tell us how it went. Have a good coding!.