Using store Cabernet in primary

[Berry Juice]

I was just given a Gallon of store bought Cabernet and thought about using it in a primary with 6lbs blackberry & black cherrys along with all the chems used in making DB.
Will this work? Any suggestion on what to add to it?
thanks

 

[sour_grapes]

Just making sure I have this right: The "store-bought Cabernet" is finished wine? And you want to add some blackberries and cherries, and ferment the sugar that is in the fruit? I really don't think you will be able to get a fermentation going.

If you have a different thing in mind than what I described, could you clarify?

 

[Berry Juice]

Correct, the Cab is a finished wine in a gallon jug.
I just thought about using it with 4 gallons of water and 6lbs of fruit.

 

[JamesGrape]

Make 4 gallons of DB to completion and then blend the cab into it per your taste?