I'm trying to put together a USDatetime Module for future release and am using a series of Extensions to get the job done. I've run into a bit of a problem that I'm hoping someone can shed some light on.

When trying to add an extension to DMYDateField (which is a child of CalendarDateField, which is a child of DateField - both of which have extensions), I'm only getting one confirmed extension ... the DateField extension. If I comment out the DateField extension, then it defaults to the CalendarDateField extension. It's looking like this:

class A {}
class B extends A {}
class C extends B {}

A::add_extension()   //   no problems
B::add_extension()   //   A extension only
C::add_extension()   //   A extension only

Any ideas on why this is defaulting to the top parent extension? Or better yet, how to implement this sort of behavior?

Thanks!
John