Sometimes certain trains don't layer in correctly (e.G. BR218 doesn't layer in the Maintalbahn unless you have Hamburg-Lübeck for something reason) and sometimes certain trains aren't supposed to layer in but should (BR420 on München-Aubsburg) But especially the DB BR 101 Expert, which should automatically substitute all DB BR 101 Classic services on ALL routes. Let us, at any time of the day, spawn a train and have an option for it to substitute a timetable service. What I mean by this is, that you could make any train substitute a service (so you would stop at every station for that service) but without fixed timing (the time between stations and the dwell time would adjust for the time of the day) e.g. The original service for the Classic 101 is 07:25 Kaiserslautern Hbf-Mainheim Hbf, and it stops at a middle station at 07:55. You spawn an Expert 101 at Kaiserslautern and use free roam timetable for that service. You depart at 09:12, so you should stop at the middle station at 09:42. So the times would be dynamic, as to mimic a timetable, and all original stops are still marked down and an objective.
Well there are reasons why the layers you mentioned don't layer or substitute The 218 requires another route to get the appropriate coaches to layer into a modern route. The 218 doesn't come with modern coaches. The expert 101 can't sub into any 101 service. It wouldn't be compatible because of the cab car and that it is study level. The simulation of the expert 101 only works with expert coaches, not standard ones because of differences in what it being simulated. The cab car prevents substitution as a whole The 420 doesn't layer into hma because of performance issues.
