title: Overriding Joomla 3.0 components. Possible to override model and controller too? Not just views?
body: <p>I understand the ability to overide core views in Joomla using overides, but how about the models and controllers? I would like the ability to add a field to the core user registration form, but Joomla pulls all the fields from an xml located in the models folder.  I could just create a plugin, but that creates its own section, and I need it to go exclusively in the main registration form, as I am creating a tiered registration.</p>
  
  <p>My question is exactly how the title implies, can you create component overrides of model and controller files in joomla, rather than just views?</p>
  
  <p>Further, I know I "could", but in the event of an update I want to make sure this is an acceptable override solution - not just a hack that will be subject to be overwritten.</p>
  
  <p>Thanks!!</p>