ᐅ Expansion joint perpendicular to the running bond pattern

Hello, I am looking for a solution to a tiling problem.

I want to install new tiles (slate) myself in my 30-year-old house.
The tiles measure 40 x 60 cm (16 x 24 inches) and are to be laid on the floor in a third-bond pattern.
In the old tiles, there are three movement joints in the middle of the room.
The room has a U-shape. The old tiles will be removed down to the screed.
The room has underfloor heating.

Two of the joints run perpendicular to the tile pattern.
Problem: movement joints running straight across the third-bond tile pattern.

My idea is to bond a thin waterproofing membrane with silicone over the movement joints directly onto the screed.
I would grind (mill) the screed slightly in the 1–2 mm (0.04–0.08 inch) area where the movement joint will be covered to avoid any raised areas.
After laying the tiles on the waterproofing membrane using C2FT S1 tile adhesive, I would cut through the membrane again along the tile joints near the movement joint.

My hope is that this approach will transfer the straight movement joint to the zigzag (third-bond) movement joint of the tiles.
The tiles spanning the movement joint in the screed would then “float” on a thin silicone bedding.

What are the possible disadvantages of this method, apart from the shear forces in the movement joint that might not be properly absorbed in the tile joint?
Are there any other alternatives to covering the entire floor with expensive uncoupling mats?

I appreciate any constructive feedback.

I am always amazed by those asking questions who skip the "call a professional" step, but I’m happy to do it for you and advise against buying an ERNSTL. Instead, I suggest bringing @KlaRa into the discussion :-)

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The floating silicone structure doesn’t sound very durable, if it holds up at all.
I would cut the tiles at that point to realign the screed joint within the tiles.
Try drawing the room and the joints.

The red lines represent the joints.

The blue bar indicates a wall that will be tiled all around.

Since the wall changes the proportions, I would tile with the joint (that is, parallel) rather than perpendicular. Otherwise, the room would stretch even more in length. That way, you avoid that problem.

As far as I know, there are special systems for this. Check out Schlüter...

@ Tolentino

There are three expansion joints.
Which one do you mean?

edit:
I want to lay the tiles parallel to the central wall.
So the longer side of the tile will run from left to right.
The room should appear longer from left to right.