Trix is made by Marklin - it's their 2-rail range.
As far as I can tell, they are compatible.
Only change the wheelsets that cause derailments.

Thanks guys!
What about the couplers ( have not received the cars yet) are they the same as Marklin?
I imagine they use the sane picket if the couplers are different…

@egonzinc
Coupler pockets (NEM = Normes Europeenes de Modélisme) are after an internional standard defined by MOROP MOROP is is a European association to define standards so that adhering companies (Märklin, Trix and others) propose fully compatible rolling stock, track, track pieces, etc

Nowadays, NEM pockets are in association with a cinematic arrangement to increase the distance between vehicles depending on curves
The NEM pocket allows also to replace a normal coupling by an electromagnetic one (to uncouple any car, anywhere by a digital command on a decoder)

Here is more on MOROP https://www.morop.org/index.php/en/nem-the-norms.html

NEM pockets allow you to use ANY compatible type of coupling. Usually coupling are simply plugged in the NEM pocket so that a Märklin, Trix, Roco, Fleischmann vehicle can make a consist without any obstacle.

Märklin and Trix are companies belonging to the same conglomerate Simba Dickie. They use the same production tool, factories with only minor alteration for 2 rails or 3 rails (insulated, non-insulated wheelsets. Trix and Märklin couplings are EXACTLY the same.

Cheers
Jean

Recent Trix Express items use NEM coupler pockets, and have specific couplings that match the height of the standard Trix Express couplings. So these days any new Trix Express irolling stock (as distinct from locos) are the same as any other Marklin/Trix H0 items apart from couplings and wheels. Because of this it is possible to use recent Trix Express items on Marklin or Trix systems by changing the wheel sets and couplings.