groupings of modal components?

Making a Swing application, I'd like to have a modal-like relationship 
between some of my windows but not all of them.

For an example: A, B, C, and D are all frames.
1. The application opens in A.
2. From A I perform some action that opens B, non-modally.
3. Then from A I perform another action that opens C, also non-modally.
4. Then from C I perform an action that opens D, and I want C to be 
inaccessible while D is open.  But I may want to refer back to B, so I 
do not want B to be inaccessible.

What is the best way to do this?  As I understand it making D modal will 
make all of A, B, and C inaccessible, so it does not work to simply make 
D modal.

Sometimes I am frustrated where other programmers have not solved this 
problem.  In cases where I'm trying to follow the directions in a help 
window to work through the steps in a wizard, if the wizard windows are 
modal I can't get back to look at the help window.

Thanks,
Rich Hammer