As an idea for those who d/c during fights, particularly NM ones or anything instanced based: Perhaps they should allow it so you can save party information/ instance information to the server? So if you do d/c and log back on you are automatically already in the party you were in? (Instanced based events being timed, like guild leves still have their timer, so if you do not log in within the appropriate time, then I guess you would fail.) It would make sense that as long as there is a party leader, that party still exists and your name is on the roster. Also, if the party leader d/cs, someone else is automatically made leader, as it is now, so as long as the whole party doesn't d/c, it still exists.

As for adding members to an already engaged battle, maybe just "Call for help?" sort of thing?