Can I ask for permission settings for sub directory and files?

The whole reason why i bought PR4100 is to allow my company to store files in there as a main document vault. I was a bit disappointed when i found out the system doesn’t have sub-version control, but it’s fine, I will only do that manually with different folders.

Then because it will be storing all the documents and files and sensitive data all under one roof, I needed to split into several departments and hence i made different user-group and different folders.
– [Sales Dept]
– + – [Quotations]
– [Account Dept]
– [Project Dept]

Now, here comes the tricky part.
inside the [Sales Dept], there are some other subfolders where i allow the Account-group to access but not the Project-group, which is the [Quotations]

How do i do this?
I initially assumed i could have sub-directory permission being set with different user-group, but it turns out i can only assign permission to the top-parent folders.

So, can i ask for the next upgrade for this model to have the permission-feature’s changed?
I am now forced to code my own file-management-system in order to make this work, but then i hit another symlink issues because the system keeps on remove my files after reboot. (i have no idea why would the system even want to do such a thing)