Multiple Dependent Drop Downs
 

Can anyone elaborate me how I can make multiple dependent drop down.
I want to create a drop down list that depends upon two values.

And second, I have a series of drop downs, each is dependent in nature. I
have selected each to get the result. Say the value selected in the first
drop down is wrong and I changed that value as a result. But when I changed
that first value, all other dependent on that value not changed (as all the
other dependent drop downs must either show the blank cell or hyphen or
error).

I shall appreciate you, if you people resolve my problems.

Regards,
Zubair