Only see related records in drop down box

[Gismo12]

Hi All,

Lets say I have a customer tbl , a product tbl and a transaction tbl

If customer 1 owns product 1, 2 and 3

and customer 2 owns product 4, 5 and 6

When in transaction layout which was opened by related customer 1, I  want to select the products only related to customer 1.

How would I setup my drop down box to only show product 1, 2 and 3 related to customer 1

and then when in customer 2, to only show products 4, 5 and 6.

I dont see any type of filtering I could do when setting up the drop down box value list.

The products tbl does have a customer ID reference so I recon it should not be that difficult but I might overlook something here. 

The above is not quite my setup but seems easier to explain my problem.

[Steve Martino]

You'd want to search for 'Conditional Value List' or 'Dwindling Value List' on the forums.  There are many examples you can emulate.