New variant(s), then.
As in the drawing, my first thought was that it would just be possible to model the DMU line as a through station, with enough station building/waiting rooms on the platform. Yes, but just.
A terminal bay for the DMU wouldn't need the buildings to hide behind.
The terminus side has slightly increased capacity, but *looks* considerably less cramped.
In return for that, the sector plate has to work overtime.
(personal preference, no rule: I find sector plates easier to engineer and align than parallel traversers.
I've found a lazy way of doing it, no real accuracy required.)
Again, only personal feel: whether through or terminus,the single DMU line seemed a little improbable, and a matching line beyond it, out-of-use to derelict, would add a sense of a station reduced from better days.
This might be too much of a challenge for the 18" width.
That might have to be played with using full size track and temporary platforms to see what would work (only if the idea appeals.)