Can we add filter on sub/parent properties while adding a file to a Document Library ?

Hi Erdem!

I guess you have built your solution like this

Created a list containing Countries

Created a list Containing Customers (and it has a lookup column against Countries.

So far so good...

In the document library you have added a column that performs a lookup against the Customer list and it returns the customer.

Unfortunately You are not able to get the Country property from the selected Customer element and display it in the document library. As You can see in the picture below, that property is not available/selectable when You have a lookup-column.

SharePoint is not the best solution when it comes to building multiple relations. The "easiest" way for You here is to have to lookup columns in the Document library, one for Customer and one for Country. That is not a very user friendly solution but for now i think its the best option if no one else in the community comes up with a brilliant idea.

If You could use Document Sets ( which is not available yet in modern libraries) You could structure Your documents in a better way with metadata applied to the "folders" etc. This seems to be "under construction" even though it is not mentioned in the Office 365 Roadmap, however this post , where  Chris McNulty has responded, contains information about a planned modernization of Document Sets. Hope it will be available this year.