Yes bees will draw comb on fondant it’s just another food source. Bees will happily draw comb this time of year even Nucs but only expect results in relation to colony size. A couple of pints above a new box won’t hurt particularly if weather is fickle. But ask yourself do they need it! If the box below is jammed with stores score/scrape cappings adjacent to the brood area below they will shift it or convert. If they are expanding well next inspection lift a frame of emerging brood into box above and shuffle up below, that normally gets them up. You won’t be into them again until this cold passes so just give them syrup if you give them anything at all, why give them the extra work. Pouring syrup into frames works fine but is normally reserved for emergencies and putting feed in direct contact with the bees/cluster in situations when they are really starving. Finsky may use it more with his colder temps and bees reluctance to travel or use cold syrup. Ian