burning a rewritable DVD--can I add a file to an exisiting folder?

I use DVD-RW’s to store photographs after I download them from my camera. After I shoot some pics, I create a new folder named, say, “Birthday party” on my computer. Then I use Nero Express software to add the new folder from my computer to a DVD-RW that already has a bunch of folders on it.

Now I want to add just one file to the 50 pics in the “birthday party” folder that is already burned on the DVD.
How do I do it?
Is this a stupid question?

If you can’t drag the file into the existing folder on the dvd, you may have to rebuild the folder.
If you don’t have the original folder on your computer anymore, copy the original folder from the dvd to your computer,
Now add the file to the folder on your computer, so you should have the original folder with the new file in it.
Erase the old folder from the dvd. You should be able to highlight the folder in Nero and then hit the delete key to do this.
Copy the new folder from your computer to the dvd and write.

You just add it to burn in that directory on the DVD. If you didn’t burn a multisesion disk or closed it, the DVD can’t be added to. You’ll have to copy the pictures back to the hard drive and then erase the DVD. You can then burn what you want on the DVD again. This time burn in multisession and don’t close it. Open multisession DVD’s often can’t be read by devices which are not computers.