Wanting to add stuff to rewritable DVD's later, but it's rewriting everything every

[Whyofcourseit'sSarahhhe]

time? So I want to burn various things onto DVD+RW DVD's; which I did. But the full disc space at the time isn't filled up. Then I want to go back and add other things back onto the DVD when I have the time, more data, etc. The thing is, is that it completely goes over everything every time.
So what free software/program can I use that will allow me to do this (the opposite of what's actually happening)? Or what am I doing wrong?

Thank you!
I appreciate any help.

 

[TVguy]

After you record, don't finalize.