Here's how I made my elderflower;
4qt. lightly compacted flowers
Sugar - about 10 lb.(adjusted must to 1.082)
5tsp. yeast nutrient
1/4 tsp. potassium sulphite
8tsp. acid blend
I got two kettles of water to a boil then turned the heat off and put half the flowers in each kettle - stirring once in a while for 20 minutes.
I then strained the flowers out - liquid into primary and added sugar/water to = 5 gallons at 1.082. Then add everything else and wait 12 - 24 hours to add yeast (Cote des Blanc).
Ferment/stabilize/sweeten/filter/.... as you see fit!