CBQ-rules of bandwidth borrowing

Hello,

I've got the filter structure like this:

1:0 qdisc root cbq
|
------------------------
| |
Class 1:1 cbq Class 1:4 cbq
| |
------------ --------------
| | | |
classes: 1:2 cbq 1:3 cbq 1:5 cbq 1:6 cbq


I want to class 1:2 may be borrowing the bandwidth
from class 1:5 and class 1:3 from 1:6.

Is this possible with configuration like this?
Because I understand that if classes 1:2 and 1:5
are marked as "sharing" and classes 1:3 and 1:6
are marked as "borrow" the 1:2 will be borrowing
from 1:3 and 1:5 from 1:6.
Do I understand it correctly??

Sorry for repeating myself but it is very important:
I want to class 1:2 may be borrowing the bandwidth
from class 1:5 and class 1:3 from 1:6.
Is this possible? and how can I achieve it?

/kvm