Question about a 2nd PS3 account

[DealsR4theDevil]

So my GF made a user account on my PS3 to use with some games like resident evil that dont let you start a fresh unplayed game without writing over the save data.

Now im wondering if I can/should link my PS network account with her PS3 user log in or if its better if she makes her own PS network account. I want to have all the games I DLed be available for both of us but it would be nice if we could each have our set of trophies and I want her to be able to play online whenever she wants.

Should i have her make her own PS network account or link it with mine? What are the pros and cons of doing either?

Thanks