How to prevent new files while accepting the modification of existing ones

Question

I'm not sure if this is a StackOverflow or a SuperUser question:

I'm working on some application, which all have the same directory structure:

• Main directory : contains the executable, the configuration, and some necessary DLLs (references)
• Modules directory : contains the customer related DLLs, their configurations and their references (also DLLs)
• Some other directories.

This morning I had the situation that a DLL was copied to a Modules directory, blocking the execution of the application. It was quite difficult to find this.

I would like to configure my "Modules" directory in such a way that no file can be added, while I can freely re-compile the already present DLL(s)?
I'm working with Windows 10, Enterprise edition.