cheesychipotle

I see :) just the summary, I suppose, rang a bell with 39 & me

Okay, so, I hate to be that guy, but isn't this essentially that 39 clues series, for kids?

Excerpt from Wikipedia:

The novels revolve around Amy and Dan Cahill, two orphans who, upon their grandmother's death, discover that they are members of the Cahill family, whose members have shaped the history of their world. The ancestors of the Cahill family are Gideon and Olivia Cahill, whose children created the branches of the family. The branches constantly compete against each other in a hunt for the 39 Clues, the source of the family's power. Amy and Dan, along with their au pair Nellie, enter the hunt for the Clues and become embroiled in the conflict between the Cahill branches. As Amy and Dan participate in the hunt, they unearth secrets about their Cahill ancestors, their parents, and the Madrigals, a mysterious organization.

So it's kind of like that. People influencing the world, minus the clue hunt, orphans, so it's the story of the family from the inside of the four sections. And they have an ancient enemy, the Vespers, who rise against them.