They said they can’t right now in one of the live streams cause LIRR being difficult for them to get recordings and pictures so they can detail the trains.
If Dovetail were to incorporate new DLC for LIRR, I'd recommend the EMD DE30AC / DM30AC locomotives and C3 Bi-level Cab car for passenger operations on the Port Jefferson Line East of Hicksville.
but he said on discord that they were building up references and a library for the dual mode diesel locomotive cab car coach’s back in October 28th of 2018.