I am still gathering all my kit and ideas
do you have a specific link to blackberry wine recipe
lots of infor out there.
It's been about 25 years since I last made a wine.
I'd look for a Bordeaux, port or Sauternes yeast, plus yeast nutrient.
Grape concentrate - I suggest a white because it should allow more blackberry flavours through - like this:
https://www.amazon.co.uk/Youngs-White-Grape-Juice-Enricher/dp/B003E1EKIU?
Citric acid, 2.5g
Pectic enzyme and campden tablets
White sugar - 340g for a dry red, up to 1kg for a sweet desert wine - in between according to taste.
340g light brown sugar
3kg blackberries
Stalk, wash and crush the blackberries, pour 2L boiling water over them and leave to cool.
Mix in the pectic enzyme and a crushed campden tablet and leave 24 hours (this sanitises the fruit and breaks down the pectin).
Activate and add the yeast, nutrient and grape concentrate, and ferment 5 days, keeping pulp submerged.
Boil and dissolve the sugars and acid in a pint of water, allow to cool.
Strain out, press dry the fruit pulp, stir in half the sugar syrup and add the must to a demijon. Fit the airlock and leave to ferment in a warm place 1 week.
Add half the remaining sugar, refit airlock and leave another week.
Add the remaining sugar and top up if necessary with clean water that has been boiled and cooled, refit airlock, leave until fermentation stops.
When the wine begins to clear, rack it (remove clearing wine from above sediment) add a campden tablet, top up if needed and leave in a cool dark place to settle.
When fully clear, rack again and store in a cool, dark place to prevent fading for 2 years.
Bottle and keep a further 6 months to 1 year.
Before starting, make sure everything is scrupulously clean and sanitised.
When bottling, pay attention to preparing the bottles and corks, boiling natural corks with campden tablets to sterilise and swell them to reduce risk of the wine becoming corked.
IME Elderberry wine needs at least a year after final rack before it becomes pleasantly drinkable, but longer can be better. A plum wine I made needed about 15 years, after which about 1/3 of the bottles were corked.
Good luck.