Shoulder, Kua, Shun and Ni

Hello Master Chen

I have a question about kua, shoulder and shun/ni.

My question is when you are doing say, cloud hands. You show this on one of your videos here called How To Keep The Center from 3.25. You are on left leg and kua opens on left side and the left hand looks like Ni. Does this mean that the kua opening always coincides with Ni chan and closing of kua is shun chan.

Also in one of your videos I remember you say that when hip opens then same side shoulder kua closes and vice versa. What does this mean exactly with the shoulder kua closing or opening. Does opening of shouldre kua mean that shoulder is not sunk and closed shoulder kua means shoulder is not sunk?