The key to this control sequence relies on proper selection of the valves.
A typical good design for parallel transfer has the 1/3 valve at 25% and the 2/3 valve at 75% total pressure drop. Assuming this is application correct the control sequence as stated by Orion is intended to limit modulation of the 2/3 valve close to the transition point or close off point. This will minimize the potential for unwanted erosion of the valve trim.
In my area when using parallel transfer at steam pressures above 15 psi, a method to limit modulation of the 2/3 below 10% is required in the steam code.
The code sequence is easy, the program may be a little more involve then what you are currently doing. Since I am not a controls programmer I will not be of help there. The key to good tuning is the loop transition point and the timing need to be adjustable.