List of ComplexTypes?

Hi there!

I'm facing an issue here and I was hoping you could help me :)
Basically I have several complexTypes defined extending a parent
complexTypes (let's call it parentType). (using xs:extension)
Each of these complexTypes has a unique element associated to it. So far so
good.

The problem is that I want to define a sequence/list containing elements
extending the complexType.
I believe to achieve this I have to create a new element with a new name of
type parentType... But what I want really is the user of the schema to have
a sequence of any elements that are extending parentType. Is this possible
in a nice way?

Thanks in advance!