Moving between the expansions

Is it possible to move my assassin from Factions into Prophecies so I can party with my friends that only have Prophecies? Also, can I move my paragon from Nightfall into Prophecies too? Any help is greatly appreciated!

For your Sin, take this quest.
http://gw.gamewikis.org/wiki/Chaos_in_Kryta

And this one for your Paragon.
http://gw.gamewikis.org/wiki/Terror_in_Tyria

*Edit* - Added the rest of the trans-continent quests for all points of origin and destinations.

For Elonian characters that want to go to Cantha, take this one.
http://gw.gamewikis.org/wiki/Plague_in_Cantha
And Canthans that want to go to Elona do this quest.
http://gw.gamewikis.org/wiki/Sunspears_in_Cantha

Tyrians going to Cantha.
http://gw.gamewikis.org/wiki/Mhenlo%27s_Request
Tyrians going to Elona.
http://gw.gamewikis.org/wiki/Sunspears_in_Kryta

Ah, thank you SO MUCH!!! You're a lifesaver.