I gather that (some)? of the maids are going to be 'serving' finger foods in the library?  Who is a tray?  It might be fun to have one girl (perhaps one whose never been a serving tray) bringing in some special treats - where she's bound on top of a wheeled cart and rolled in?  Nicely decorated with various appealing items and also exposed for other uses?  Does that sound interesting to anyone?  Though, binding is not required, if the freedom to move would be more interesting (or the bindings could be removed).