I'm a little confused about the Brothers Seven and the Skinshaw men. According to the adventure the Brothers Seven is a cover for the Skinshaw men. It also gives the impression that the members of the brothers seven are influential and wealthy individuals.
This leads me to wonder about the cultists encountered at the sawmill. Presumably none of them are actually members of the Brothers Seven (except Ironbriar), for why would wealthy and influential members of Magnimar be working in a sawmill. I assume that these guys are just lower class killers that the brothers have indoctrinated into the cult. Is that a safe assumption or are these guys actually supposed to be members of the brothers seven?
Assuming they aren't, then in theory more members of the brothers should be in the city, and they are likely wealthy merchants or members of the nobility.
I'm trying to figure out how to deal with this because the PCs are on their way to Magnimar they know of the brothers seven and will be trying to gather information about them. I'm worried they will end up getting off track trying to track down all the members of the brothers. On the other hand, I think it would be interesting to add a bit more detail about the brothers that they can investigate.
Right now I'm thinking that the brothers will be a fairly large social club made up of members of the city's elite. However, for the most part, it is a legit social club- even the lord mayor is a member. They gather at people's homes once a month to dine and socialize. They pay dues, network etc... However the club has an inner circle (the 7). According to the constitution of the club there may only be seven members in the inner circle at once (at least that's what members of the club's outer circle are told), and members of the inner circle are only replaced when one leaves or dies. The identities of the members of the inner circle are secret (maybe justice Ironbriar is the only known member of the inner circle). Members of the outer circle spend a lot of time guessing and speculating about who might be a member of the inner circle, though they don't over do for fear of pissing the inner circle off and ruining their chances of ever moving up.
The truth is that the inner circle recruits from the outer circle, but only when they see someone who seems to have the potential make a good candidate (ie. serial killer). The lay members of the club are fed the line about there only being aloud seven members in the inner circle because Ironbriar doesn't want self-important members of the club pestering him to join the inner circle, especially when such folk aren't the sort of candidate he's looking for. For instance the mayor would think he should be a member of the inner circle, but Ironbriar could easily brush him off by saying there are no empty spots available (rules are rules). The inner circle is ultra-secretive and never let the members of the outer circle on to their true nature.
In this larger version of the brothers it seems likely that some of the members of the outer circle might be greedy targets for Xanesha, and I think a couple will already be dead.
I'm still trying to decide if there are actually any members of the inner circle still around. When the brothers were founded there were seven in the inner circle, but I'm thinking that there are now less. Maybe only Ironbriar is left, and the inner circle no longer really exists because he hasn't found good candidates of late and the former members are now dead or just too old to be effective murderers. He uses the outer circle as a means of gaining money and maintaining influence over important folk in the city, though he always keeps his eye for a potential killer.
Ironbriar still has his cult, but the current Skinshawmen are mainly composed of lowclass killers that he has employed at the mill as a cover. These individuals aren't actually members of the brothers seven, even though they are Skinshawmen.
Thoughts?
Just because one member of the Brothers Seven is a cultist and subverted the sawmill to his uses doesn't mean they all are. They can speak in shock and horror at what was going on and pay off the Lord-Mayor to brush it under the rug so not to ruin their name.