Quanto segue sembrava funzionare per me:
<input type='text' name='chapters[0][id]'>
<input type='text' name='chapters[0][name]'>
<input type='password' name='chapters[0][password]'>
<input type='text' name='chapters[1][id]'>
<input type='text' name='chapters[1][name]'>
<input type='password' name='chapters[1][password]'>
