That is implicit.
You can’t push your hips forward without balance.
You can’t open your shoulders without balance (unless you are leaning on the horse’s mouth, which would defeat the whole process).
You know, pushing my feet forward is not something I’ve really consciously thought about while in two point, I just focus on keeping my lower leg stable. I’m going to give that a try and see if it feels different. I do think about “soles of boots forward” on approach to a fence because it keeps my leg forward and on (tendency to pinch with my knees due to a really hot one that I totally admit I would chicken out on making her deal with my leg on).
May be turn this on its head. When you are travelling forward in the 2 point, your balance is over the centre of gravity of the horse. That point moves forward, the faster the horse is travelling. You are both thinking “forward”, you are telling the horse “forward”. So, if you shift your thoughts, energy, balance, weight back slightly, opening your shoulders, sitting slightly more upright, the horse can immediately feel that shift and comes back with you so as to keep a comfortable balance.
And if your horse responds to that “something” that you are doing, then it is “correct” in your particular partnership. It works for you.
your balance is over the centre of gravity of the horse. That point moves forward, the faster the horse is travelling.
The first part is (or should be) true. The second part is not. "Speed’ does NOT move the center of gravity. Sticking the neck out DOES move the center of balance, but not a lot.
Furthermore, when you push your hips forward and open your shoulders, you are moving YOUR center of gravity FORWARD, not backward.
ETA that, contrary to popular misconception, shifting your center of gravity BACK is an aid to go FASTER, and shifting it FORWARD is an aid to go SLOWER. Just watch the jockeys “stand up” at the end of a race.
Hmmm. Explain a bit more so I can understand. A walk has a different centre of gravity to a canter. Doesn’t it also depend on your seat? A jockey standing up has no seat. A two point seat is not a driving seat. I’m trying to visualise what I do to slow up cantering around a field with lots of ups and downs.