Customizing /@@plone-addsite in root

I'm currently trying to add additional fields to the http://localhost:8080/@@plone-addsite view on my Plone. I've found the corresponding Page Template, but am unsure how to overwrite it "properly". I'm new to add-on development in general, I've done quite a bit of GenericSetup tinkering and I'd also know how to overwrite an existing view with configure.zcml, I'm merely stumped as to how I can get the root to load my underlying code.

The idea is to be able to easily create new Plones under one Zope instance.

Alright, just for future reference in case anyone stumbles upon this and is unsure how to proceed.

I've not been able to customize /@@plone-addsite for root, however in the meantime I've simply opted to add a layerless view in our code such as http://localhost:8080/@@plone-addsite2. This view simply inherits from Products.CMFPlone.browser.admin and the .zcml looks like this:

<browser:page
   for="OFS.interfaces.IApplication"
   name="plone-addsite2"
   class=".admin.CustomAddPloneSite"
   permission="zope2.ViewManagementScreens"
   template="templates/plone-addsite.pt"
/>

While it's not equivalent to overwriting the original view, it's good enough for what I'm trying to do. When attempting to layerlessly implement a view that's already taken, Plone simply crashes, though I know it is also possible to do overwrites on a root level, since I'm fairly certain that collective.solr does something similar with the default search view of Plone, though I've not been able to replicate the behavior.

When you don't use layers to make your registration more specific than already existing registrations in the ZCA (zope component architecture), you can use overrides.zcml.

Plone doesn't crash but gives you a traceback because it cannot decide for you which of the two equivalent registrations should win. ZCA is mostly declarative and tries to avoid 'the last registration wins' behavior like css specificity.

I cannot seem to figure out how to use the overrides.zcml. The documentation on overrides seems to simply state that I should create a file in the same folder as my configure.zcml. I have done just that, but to no avail, as it simply fails to load whatever I write in my overrides.zcml. Am I doing something wrong?

Here is an example of how it could be done (sorry for the comments in pt_BR, but other than that it seems to be quite easy to understand)

Plone Foundation Code of Conduct