Stu H,
The only thing I am puzzled by is why feed fondant below sugar syrup stores.
With a brood and a super there should be more than adequate stores for colony (20kg is a normal target for stores for the winter and into spring) until late Feruary (most normal years!). But if a colony is reported to be using just 100g of stores per week (recent post), over this last two weeks, your stores will last until serious brooding is well under way in the spring (they may need extra protein to be able to utilise all that sugar honey).
Personally, I would think half a kilo per week is more like an average usage until brooding starts in the warmer weather (mine certainly do not follow the solstice theory. Two years ago there were bees with no brood into the second half of February). This year I would think all normal colonies have now stopped brooding. When they restart is anyone's guess!
Regards, RAB