So what you're saying is something like:
B. When the disc is released, a player must:
1. Make contact with a stance zone defined by a 30x30cm square (or variant, or existing lie) directly behind the marker disc with;
a) at least one supporting point that is in contact with the playing surface or,
b) the next subsequent supporting point contact with the playing surface; and,
2. Have no supporting point contact with the marker disc or any object (including the playing surface) closer to the hole than the rear edge of the marker disc; and,
3. Have all supporting points in-bounds.
C. Supporting point contact closer to the hole than the rear edge of the marker disc after the disc has been released is not permitted and is considered a stance violation. The player must demonstrate full control of balance before advancing toward the hole.
No need for D.
Slightly ugly wording, but you get the idea I hope.