Currently, adding trains to a group seriously messes with the LTN stations logic.

Not sure about the feasability of keeping these two sytems (LTN & Train groups) from interfering with one another, but would be pretty cool if they didn't.

LTN wants to dispatch trains individually, so train groups are fundamentally incompatible with LTN. I added code in 2.3.3 that, if a train is in a train group and put under LTN control, it will be removed from the train group. That should at least clear up the confusion when a train arrives at a LTN depot, is put under LTN control and suddenly all trains in the train group behave weird.