@Maky_Boi
Not sure if this was changed in an update. We used to couple them in the exact way you said (i have to admit though it has been a while since I last spawned one in from the build zone). What I recommend (and also what we do when we need a TGV) is that we just create a quick spawn location and use the test mission feature to quickly get a train out. This works great and also makes it easy to have a longer train.

How do I couple everything together because when I spawn the front locomotive its alright same with front wagon but the rest share wheels but if i back too close up to the train spawn area it will delete the wagon thats too close to spawn the middle one