Inheritance question

Base extends MovieClip
document class extends Base

how would Base properly access a display object which is already placed on stage in the flash ide?

for example creating the var in Base’s class definition =
1152: A conflict exists with inherited definition in name space public.

but just referencing the var = 1120 undefined property , as the item is only a variable of the document class

Is the only approach to let the classes load, then create the display object rather than have it on stage already?

thanks