>>919554>>920006Those aren't steam helpers and you don't coordinate that power. The GN's electrified system was build to assist GN freight and passenger trains through the Cascade tunnel. The exhaust from steam trains were a real nuisance and health hazard back in the day in terms of ventilation in the tunnels and so GN built the electric system as way to avoid the need to run steam trains through them. The steam locomotives would basically be idled while the electrics would do all the work. The electrics were the "helpers" in the sense that they had a purpose limited to getting trains through that stretch of mountain tunnels. The electric motors would decouple from the steam locomotives after their job was finished and the train would continue on its journey.
https://en.wikipedia.org/wiki/Cascade_Tunnel#Original_tunnel 