Well if blackberries grow there, maybe try a known variety of BlackBerry Bush to replace tbem with after you reset the area
Discussion
We might do blue berries instead
Do blueberries grow well where you are?
You know the blackberries grow well in that particular spot.
I would just hate to put in money and effort trying to get blueberries established if some blackberries with better genetics would be an easier solution.
On the other hand, blueberries are freakin awesome after a few years getting established
And might as well do a thornless variety.