Don't know if this helps, but I make elderberry vodka by using 1 litre vodka, 1lb elderberries and 1 lb sugar. put all together in cleaned 2 litre coke bottle. Leave to mature for about 3 months, ie from autumn to Christmas, then strain and bottle back into original vodka bottle. Use cheapest vodka available. You will end up with more than a litre of new vodka so have another bottle handy. Makes a sweetish alcoholic drink like a thinnish liqueur, so you can change recipe next time to suit your tastes.
My b-in-law does same with raspberries, and makes sloe gin in the same way with same quantities of ingredients, so have a go and experiment. You may need to prick the damsons to release the juice.