Replacing files within a folder, rather than the entire folder

Forgive me if this has been answered before, I searched around and couldn't find anything on it, but I wasn't sure exactly what to search for, so that may have been it.

Anyway, I have a question. One of the things I miss about Windows is when you replace a folder with another folder with update files, it replaces the files within the folder, rather than the entire folder itself. I'd like to see if I could achieve this same functionality in Mac OSX.

I'll give an example, becuase that may have been a little confusing.

I have Folder A. Within Folder A I have Files X, Y, and Z. Company Q releases an update to some of the files in Folder A. When I download the update, its a zip file with Folder A and updated Files Y and Z. In windows if I simply drag the new Folder A over the old Folder A, Files Y and Z would be replaced with the new versions, and File X would stay intact. However, in Mac OSX if I overwrite Folder A with the new Folder, I would lose File X.

How can I have it so overwriting a folder replaces the files within the folder, rather than the entire folder itself?

That doesn't sound right at all. However, the easiest way to do it is to open the new version of folder X, hit command-A to select everything, then drag them all into the original folder X at the same time. I'll have a play later, though, because it shouldn't delete files within a folder like that at all.

Open up the new folder, drag Y and Z to the old one, and you're done.

Yeah, thats what I've been doing. Sometimes though theres folders within folders. I was just trying to eliminate redundant steps

I've lost many of files when I first started using osX because of this. It's really the only thing I don't like about osX. So far, I haven't figured out a way to do it anyother way.

Giving this a quick bump to see if there are any other ideas.