? Adding to an Open (JPG) DVD

Hi,

My mother got a copy of a DVD with some birthday pictures. It’s only using 128MB. It has one session with one track, but the disc itself is still open—which is probably why the DVD player (which supports JPGs) says it is an unknown disc. She wants to add some more pictures/video/music to it.

Unfortunately I don’t know how to use an open disc since all the work I’ve ever done with CDs and DVDs over the years has been single-session tasks (I file and prepare the disc and burn, then close it).

How can I help her out? Is there a way I can replace the existing session with another one altogether, sort of like how packet-writing is possible on non-eraseable discs?

Thanks a lot.