Yes! I think the ISOs are more or less exactly like Users in ability-- they just don't have access to... well knowing the codes and The Grid from the outside in? In the movie when Quorra's arm was getting replaced, she had digital DNA, and was able to utilize the portal to go to the real world just like Sam and Kevin could, so who's to say that she won't be able to use computers/alter the Grid from the outside.

And even just discussing ID discs with security_sym has gotten me a bit confused, so you are not alone! I think though that a forged disc could work like a back-up copy? I also talked with sym about encrypting incriminating data, which makes a bit more sense as to why they would need to be forged in the first place. I don't know, really!