I want to attach a wall to a floor as shown in the picture. The wall has 2 layers. The Finish-Layer is supposed to cover the floor. (Now done by using the function "Top Extension Distance" for the finish layer.)
I am searching for a solution that allows me to change the shape of the floor. The wall should then follow the shape of the floor.
I think I understand your problem. You wish the walls to move with the floor sketch and walls together.
You don't need to use wall top extensions to achieve the results you are after. All you need to do is...
Edit the sketch of the floor and align and lock the dimensions to the 'centre' line of your wall build up. Then join the wall to the floor. Providing all the layers for the floor are within the Core boundaries of the floor it should have a higher priority than the inner skin of your wall.
You can move the walls and the floor boundary will follow. If sketch lines within the floor sketch are deleted and recreated they will have to be aligned and locked again. You can move the walls to control the floor boundary but not the floor boundary sketch to control the walls. If you alter the sketch it will lose it's constraints.
Hope this helps,
K