I usually use same weights of fruit and sugar to make jam but yesterday misread the scales and added 2kg of sugar to just over 2lb of plums. Whilst it has set OK it is rather too sweet - can I use some more fruit and then add this to the existing jam and boil until setting point is reached again? I have had to do this when I haven't achieved a set due to too little pectin and added extra lemons but never because I have added way too much sugar :-(