Shared itunes: Two or one?

My stepmom just got an ipod. We want to share my 140 songs but not money. I want to still have my songs but she can have them too, and i dont want the money to mix together. I know this is possible because I did it with my brother, but he wont tell me how to. Should she make an account and will it let her have my songs too? or will that make us share money? Help please.