Hi williamseal, once again thanks for the acknowledgement, I'm only too glad that you find my comments helpful. I won't be at the event in Oxford and incidentally Azed is one of the puzzles I don't do.
You're spot on that entries that traverse the amended 4d are affected. If you use the mechanical definition of the amended 4d things should become clearer.
For example a 10 letter answer is split into 2 5s. The first 5 letters entered in the LHS of a row where it fits; the 5th letter intersecting with 4d and the 2nd 5 letters entered with the 6th letter of the answer also entered where it intersects with 4d but a different row. Hope this helps.