Hello guys!

I'm dealing with a huge problem over here and after had spent days trying (without success) to solve it, I'm now looking for expert's help.

I got a spreadsheet which is composed by multiple lists and dependent sublists.
Here it goes a detailed explanation about my problem:

****************************************************************************
The first list name: ACTION
Values: USE
VERIFIFY
****************************************************************************
The second list name: FUNCTION
Values:
If "ACTION" equals to USE, available values will be:
FUNCTION 1
FUNCTION 2
FUNCTION 3
FUNCTION 4
FUNCTION ...

If "ACTION" equals to "VERIFY", available values will be:
FUNCTION 5
FUNCTION 6
FUNCTION 7
FUNCTION 4 !SAME FUNCTION WHEN ACTION=USE!
FUNCTION ...
****************************************************************************
The third list name: SUB-FUNCTION
Valores:
If "ACTION" equals to USE and "FUNCTION" equals to FUNCTION 1:
SUB-FUNCTION 1
SUB-FUNCTION 2
...
If "ACTION" equals to VERIFY and "FUNCTION" equals to FUNCTION 1:
SUB-FUNCTION 3
SUB-FUNCTION 4
SUB-FUNCTION 5
SUB-FUNCTION 6
...
If "ACTION" equals to USE and "FUNCTION" equals to FUNCTION 2:
SUB-FUNCTION 7
SUB-FUNCTION 8
...
If "ACTION" equals to VERIFY and "FUNCTION" equals to FUNCTION 2:
SUB-FUNCTION 9
SUB-FUNCTION 10
SUB-FUNCTION 11
SUB-FUNCTION 12
...
****************************************************************************
Nome da quarta lista: LOCATORS
If "ACTION" equals to USE, "FUNCTION" equals to FUNCTION 1 and "SUB-FUNCTION" equals to SUB-FUNCTION1:
LOCATOR 1
LOCATOR 2
If "ACTION" equals to VERIFY, "FUNCTION" equals to FUNCTION 1 and "SUB-FUNCTION" equals to SUB-FUNCTION1:
LOCATOR 1
LOCATOR 2
If "ACTION" equals to USE, "FUNCTION" equals to FUNCTION 1 and "SUB-FUNCTION" equals to SUB-FUNCTION2:
LOCATOR 1 !SAME FUNCTION AS WHEN SUB-FUNCTION=SUB-FUNCTION1!
LOCATOR 4
If "ACTION" equals to VERIFY, "FUNCTION" equals to FUNCTION 1 and "SUB-FUNCTION" equals to SUB-FUNCTION2:
LOCATOR 1 !SAME FUNCTION AS WHEN SUB-FUNCTION=SUB-FUNCTION1!
LOCATOR 4
****************************************************************************

I really need your help guys, my brain is "on fire"!

Thanks in advance!