Are you wanting to add sugar to a must that you are going make into wine or are you adding sugar to a wine to sweeten it?
If you are creating a must then the sugar you add does not effect the body. It effects the amount of alcohol you will end up with. You will need a hydrometer. It is a cheap and very easy tool to use. Process your fruit, for instance your plums, crush it and mix it into the water that you are going to use. Check the hydrometer reading. You may need to squeeze some juice through a strain bag to get the worst of the particles out.
You mentioned Balling. It is just a scale for measuring specific gravity which tells you how much sugar is in the must. There are 3 common scales: Specific Gravity, Brix, and Balling. They are just different scales for the same thing. Not many people use balling. I prefer specific gravity or SG. If you measure your SG for your plum you will probably get something like 1.020.
Now decide you much alcohol you want to end up with. For plums I would recommend between 11 and 12% alcohol for a dry wine or 13% if you want a sweet wine. Higher and it will tend to be hot and cover up the plum. Look in a hydrometer table and you will see that you need an SG of 1.090 for 12%. This means that you must raise the SG by 1.090 - 1.020 or 0.070. You will need a specific gravity table for winemakers. You will find one at: Here you must be careful. The table indicates that to raise the SG by 70 you need to have 1 lb 8 oz in a gallon or 1 lb 11 oz added to a gallon. Since you already have your water in with the plums you want to use the 1 lb 11 oz added to a gallon.
Stir well and then check the SG again to be sure it is 1.090.
Ray
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