How do I transfer songs from both of the ipods?

We have 2 ipods at home. My mom has 80 Gb and I only have 2Gb. She has most of the songs I’ve ever DLed. I want to add them to my ipod, but I don’t seem to know how. Do I need a program for this? Does the program work? I don’t want to download something that crashes my computer. Please Help!