Sorry forgot to mention it was with affinity designer, not affinity photo. I'm working with curves and shapes, didn't see any option to do what i'd like to achieve
I want the middle not to move. The reason i want it in the middle is that the top and bottom are actually part of a hat i made, so there is the front of the hat and the rear of the hat. The middle layer is my character wearing the hat. So i want the front of my hat to cover the forehead of my character, but i don't want the rear (which actually is more the inside of the hat, and the hat is wear slightly bended rear) to cover my character, just the side of the rear of the hat to appear on the side of my character head (it actually just serve the purpose to add some depth to the hat, i added some shadow inside this layer).
I figured out i could select both top and bottom layer with shift pressed, but i wondered if there was a simple way to associate those 2 layers so that they move together when i want to adjust the position of the hat on top of my character head