Just started to work on doing a complete brake job on the car.
e-brakes, rotors, pads, calipers, flex brake line in wheel well areas.

History: car sat still for 2 years non use. Hence why the redo.
Today attempted to take the flex brake lines off the rear of the vehicle, but they will not come undone at all, extremely rusted, corroded and the line are dried out and cracking severely.
Attempted to undo the connection at where the solid brake line meets the flex line, but all that happened was stripping of the flex lines sides. Ended up going from a wrench to a pair of vise grips with some heat and it still would not break free.
What are my options at this point and time. I don't want to be replacing complete solid brake lines as well since they are protected under the car.
Can I cut the solid line near the connection point and make a new connecting end?
Options and directions needed. Thanks.