I normally brew bitter in a barrel but decided to brew some lager in the anticipation of an indian summer!

I am going to bottle it in the next few days but have a question about the priming. The bottles i am using are various sizes from 750ml to 2ltr so I can't be bothered to measure out the sugar for each bottle. I have decided to work out the amount of sugar for 23 ltrs and add this into the fermenter before bottling. I know this needs to be dissolved in boiling water prior ro mixing but how much water should it be dissolved in? Too much water will dillute the brew so i want to get this right!