First ask yourself why they had so much excess stores after winter. These stores were good for last winter? So should be good fo next winter, but better used in the season for nucs and feeding if there is a break in the forage available.
The simplest way is to give them the frames! Can't think of anything simpler!
But somehow, I am thinking you fed fondant when they did not need it or they went into winter with far too much stores, or you did not extract enough honey at cropping time.
I feed back shallow frames of stores under the brood in autumn, rather than feed sugar. The frames might be left over the winter, but I generally give them plenty of time to re-organise those stores for themselves.
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You seem to know more than I do Oliver (not) I fed my bees no fondant as they had plenty of syrup, The problem was that after feeding them there was a reallly long mild spell and the Ivy kept giving and giving and the bees kept storing and storing, hence the brood frames where bogged down with the stuff. I have of course fed the nucleus's and swarms of unknown origin this after 3 days but I am still left with an excess which as I said I will feed to the bees in autumn.