Where I work, the network "folder" is owned by the Division, but I need to be
able to update or add content for my Department

So, the IT folks created a network permission that I may do anything at all
inside that folder... with files that begin with the 5 letters that indicate
the file belongs to "me" and not to the "folder owner"

You own the website, so you put in a permission that "someone" or "anyone"
else may add or update or delete files... as long as they begin with FinDept
(or whatever you need as identity)

I have no idea how our IT staff created the permission rule for me... I just
know that as long as I put our 5 letters on the front of the file, I may do
anything I want to just those files, and not do anything at all to any other
file