It could be the manager, or a new noble, eg. a foreman.
All he has to do is inspect jobs that are pending for too long, and make sure that some dwarf has the right labour setting.
I've considered the possibility of the Manager, Broker, and Bookkeeper all having the ability to nominate assistants, whose appointments would be confirmed by the mayor/player.
Assistant brokers would fulfill the obvious function of standing in for their boss & his notoriously inconvenient sense of timing. (Granted, "Anyone can trade" already does this, but who wants to see their gem-encrusted gold goblets sold off by a 14-year-old Lye Maker?) In the rare event that the broker actually
does make it to the Depot in time, his assistant will still try to be there as well, for the Appraiser training that comes from watching her master haggle.
Assistant bookkeepers would do the legwork required to make meticulous record-keeping actually realistic. Instead of your bookkeeper mysteriously gaining real-time infinite clairvoyance simply because you kept her locked in her room playing Sudoku for a couple of months, the bookkeeping screen (
i.e., you) doesn't know about that just-mined lump of orthoclase until it gets dumped in a stockpile, one of the assistants arrives to assess said stockpile, and then he returns to the office to report his findings to the bookkeeper, who adjusts the great ledger accordingly.
Assistant managers would similarly roam the fort, notifying workers of new jobs and yelling at the ones that seem too lazy. Helpfully, they can combine these duties with related hauling--if they have to go down to the smelters & tell them that boss wants 20 bronze bars, they can make a quick stop at the woodpile and drop off some charcoal needed for the very job that they're announcing. Also, it might be interesting/useful if the work orders gained
persistence proportional to the number of assistants: That is, a managerial order will not be cancelled until
all of the assistant managers report its failure.