The rules are very clear on this. If you are already in an official mission you may NOT participate in another official mission. Calling dibs is the exact same thing. You are taking a slot away from someone else that might want to do the mission but isn't already in one.

If you manage to finish the mission you are currently in, and there is a spot left in the mission; THEN you can take part in the other official mission.


PLEASE remember that you are NOT the only member in this guild, and it's not fair if you hog all the missions.