However, she may not be in attendance if she has become Jarl of the Rift beforehand through capturing Fort Greenwall during the Skyrim Civil War quests. Other people the Dragonborn has done favors for might be in attendance, including other Jarls. Some might be persuaded to make a distraction...
You get the quest "Diplomatic Immunity" from Delphine after completing the quest "A Blade in the Dark". Delphine believes that dragons are coming back to life and only the Dragonborn can stop them. It turns out she was right. Near Kynesgrove, we saw a dragon shouting another one back to...