Package Declaration

[Namespace]

Currently i have all of my Files in the same Directory.
Now i will split them up in several specific Sub-Directories, 
e.g. Graphics, System and so one. But i have a problem: Some 
Files of one Sub-Directory call methods from Files which are in 
other Sub-Directories.
Up to now i have no problem, because if all of them are in the 
same Directory i can define the method under the "package" label 
and any other Module in the same Package can access the method.
What if I have Subpackages? E.G. Namespace.Graphics.Foo will 
access a method in Namespace.System.Bar. "package" doesn't work 
anymore, although they are in the same main Package. Ist that a 
Bug? And what should i do?
In C++ i can use the friend declaration and i thougth i D 
"package" are the equivalent.

Sorry for my english.