There is evolution in many aspects of our lives. Our beliefs, thoughts, and feelings are in a state of constant evolution. It's a state of change. When our lives are in perpetual movement, our destinies cannot remain constant. Destiny is evolving.
As a start, we need to understand the meaning of destiny. Destiny is the future course of our lives, and path, which is determined by the superpower. The superpower implements the destiny based on past, and present actions (karma). The superpower hence is the implementer of our destiny. Only he has the power to reward, or punish based on the principle of karmic justice.
So, let's move to the next question - who creates the destiny? The answer is simple - man. Man creates his destiny (future) through his actions. He is given full freedom over his actions. He can do good or bad. The power is in his hands, not in the hands of the superpower. The freedom he has over his actions makes him fully accountable and responsible. Hence, he bears the resultant consequence. Man can never blame his destiny because it is like blaming himself. It's like blaming his past actions. So, man creates his destiny through his actions and karma. Man creates his future. We thus conclude, man is the creator of destiny and his creator (the superpower) is the implementer of destiny.
The present state of man's actions are a mystery. Most men themselves don't know how they will behave in the present. Such is the whirlpool of emotions. Such is the instability. In this churning, there is no constant. The present has no constant. It is being watched by the superpower. He is watching how man uses the freedom of his actions. Based on this, the future destiny gets created. This future has no constant either. It is also subject to modification as man's present evolves. Hence, destiny is evolving.