Adding pictures to DVD

Hi, I am a retired insurance agent who likes using the internet and also taking digital pictures and video. I have backed up my data files to a DVD+rw and my pictures to another Phillips DVD+rw disc. Now i want to add some more pictures to the original disc but i wonder if i have to reformat the disc or is there some way to add new files?

if your dvds were created using multisession you just start a new session.

ht fireman will do mulitsession dvds too [and it free]