Hi, I've a script exteding the main page class

class CustomExtention extends DataExtension { }
+
Object::add_extension('Page', 'CustomExtention ');

All good, however, on a site where there is another module already extending the 'Page' class, this 2nd extension doesn't seem to be picked up

Is it only possible to have one dataextension on any one class? If that's true, is there any kind of work around?

You can have as many extensions on a class as you want. Make sure you have an add_extension() call for each of the extensions. You'll need to flush=1 when you add a new class to get it added to the manifest.

cool, seems to work now using to add some content into the header...

public function contentcontrollerInit($controller) { }