If you truly want to “force” the template, you could do it with a plugin attached to OnDocFormSave. Something like this (where 12 is the ID of the News resource and 6 is the ID of its template):
<?php
if ($resource->get('parent') == 12 {
$resource->set('template', 6);
$resource->save();
}
This would ignore any template the user has selected and force the one you want.
You could duplicate the above code with new ID numbers below the code above if you want to force the template for other pages.