How to improve Park Brake Performance with Dr Diff Rear Wheel Disc Conversion?
I had Ford rear disk back in the day.
The parking brake had a self adjuster that had to be turned back in on a pad change. To do that you had to remove the lever on the caliper, turn the piston with a special wrench then put the lever back on.
I don't know the dr diff brake parts but if it uses the caliper to press the pads then there might be more adjusting you need to do. If it has separate drum shoes inside the center of the disk rotor check for pad alignment and adjustment
You mentioned you could press the foot brake and get a few more clicks out of the parking brake. That suggests to me the adjustment is the issue