First of all, I apologize for the nonsensical subject line; not sure how I managed to do that. I think it's supposed to be "Bringing Westcrown to Life," but I'm not sure if it can be changed at this point.
As for the Children of Westcrown, it seems to me that their vision is ultimately for the people of the city to save themselves. Their home is not only plagued by monsters, but threatened by rising crime and a government too corrupt or incompetent to protect its citizens. All around them they find only short-sighted selfishness, apathy, and despair, but by striking back against the problems plaguing the city, they hope to inspire a movement for change and reform that might save their dying home.
Rules-wise, I've been toying with the idea of adapting the revolution mechanics from Hell's Rebels to model the activities and growing influence of the Children of Westcrown. While they're not a rebel group, the Children are operating outside of the law, trying to mobilize support among the citizens of Westcrown without attracting the attention of the dottari or the Council of Thieves, so it seems like a good fit.
Naturally, I'd need to significantly revise the events table, at the very least, but I think the rules could be an interesting addition to the AP, even if they're not as central to play as they might be in Hell's Rebels. The members of the Children of Westcrown at the beginning of Bastards of Erebus seem like they could easily represent a team of Street Performers (though I think I'd rename them "Eavesdroppers") and a team of Peddlers, giving the PCs some help in gathering information and the monetary resources to start expanding their operations without necessarily dipping into their own funds.