[DB2] multiple dowropdown menu (select)?

Hello,
I have a form with 3 selects:
1- type
2- brand
3- product

When I select the type (online, offline) select 2 (brand is populated);
When I select the brand (brand1, brand2, brand3) the product select is populated.

I already created a 2 level dependent doropdown, but I have difficulties creatinf a 3 levels dependent dropdown selects.

What is the right approach?
I actually added the 3rd level to the parent page (static-plugin) but I suppose I should add it to the 2nd select (static-plugin child).

Or am I missing something?

UPDATE:
I managed to get something similar to my needs.
The only problem is when, after selecting the third level I change my mind and change the first level.
Actually changing the first select will populate/reset the second select, but not the third select.
How can I make changing the first select resets/repopulate the second and third select?

This kind of a problem was easier to solve in DB1. =(.
Tony