Guild Wars question

Hi all.

I'm going to start playing GW again after quite sometime away and i have a question. I only own factions and not the first game and the new one. If i ever buy them in the future, does that add new content onto what i have?

Would i need to register them to my account?

yes, it does add content, you can add your new prophecies key and/or nightfall to your already existing factions account. To do this, go to the login screen and click "Add access key". Type the key and follow instructions and it's done. From then on, you can travel between the three worlds via Lion's arch in tyria, Kaineng Center in cantha and kamadan in elona.

You can either use the other games cas stand alone accounts (basically how your nightfall is now, unlinked to any other game) or merge them into your Factions. With each one you add your characters gain access to their lands, professions, skills, equipment and share storage. Adding an access key from Prophs or NF will give you 2 more character slots (P+F=6, F+NF=6, P+F+NF=8) and there's more that I can't be bothered to mention.

would also add a new contient as well as new skills.