Double, conditional data validation. Related to each other.

Hello all,

I have this problem, which seems really simple and obvious to me, but i can't find a way to make it to work, so last help is to use the great online knowledge you all have.

Ok, situation is as follows:
Imagine someone who builds cabinets, and calls them according to citynames.

While they all have a different way of producing the door, some can only made out of solid wood, where others only can be made out of plywood/sheet. Then at last, some can be made using both methods/materials (solid wood as well as plywood/sheet).

Now, i would like to use two ranges of data validation, where the user first selects the style(=city), and then, gets the option to chose the material, but only for the possible building methods.

So, for example, when someone choses Amsterdam as style, they can only select Solid woods as materials (so options would be Birch, Oak, Cherry), the plywood materials won't appear in the list

But, when someone choses New York as city, all options, should be available to chose from (Solid wood materieals as well as plywood materials).

So, concluding this whole story; the actual problem is to get the desired list in cell C11...

How can i possibly achieve to get this as wished?

I added a dummy file as attachment.


Thanks for your help!
Best regards,
Arno