Best of luck! My broody girl seems very determined. (Maybe she heard the chicks indoors?). My husband suggested I try to stick some of the chicks under her. I think I may try it, with supervision.,..of course. Probably won't work, but it would be an interesting experiment!
When that doesn't work, I'll probably need som eggs. Is it possible you could bring some to your work?
A word of caution if it is ok.... I have found broodies tend to be more accepting of foster chicks if they have been setting on fake eggs for about 10 days or more. Although broodies can't count it does seem their hormone levels fluctuate and they sort of have 'stages' during the brood and can be quite flustered if they suddenly have peeping and cheeping when they weren't expecting it.
If she hasn't been sitting very long it may take more time and supervision to get her to adjust to suddenly having chicks, it can work though.... best chances are if chicks are less then 2 days old or so because they get used to brood lamps and get scared easily by a broody hen. Be prepared to help the little ones back under mama hen quite a few times until everyone gets used to the new arrangement.