Thank you so much Wacky Toaster, for your help.
The file I shared is the latest version but is not working as expected.
This is how it should work:
The next room should only be visible when the player goes over the teleport object. Then the room is changed to the next one, and the player is standing in the doorway.
When I move the player push by push, he is pushed back by the teleport object.
The whole labyrinth consists of 7 sub-labyrinths, which contain 12 chambers each. Those chambers are invisible to the player when he is not in the chamber. So only the chamber the player is in must be visible.
Each sub-labyrinth is one layout, so there are seven layouts to accommodate the labyrinth.
I think I have to go back to the drawing table and design a better method to change rooms.
Thank you for your help which is much appreciated.
Chris