I often wondered why Shellharbour Junction was so named when it apparently started life as Dunmore. I couldn't find any evidence of an existing or previous rail junction, and now 303 has confirmed it.
You should have "Dunmore" research. The station called Dunmore started out as Shellharbour.
There is a funny story (too funny to be entirely true) regarding David Hill, the State Rail CEO doing "undercover boss" trips around the network to see it from a customer's POV. One day, he decided to visit the seaside spot of Shellharbour, which he had heard a bit about. So he caught the train to Shellharbour, and got off the train on the single platform that was there in the middle of farm paddocks and no sea view to be seen. He asked the Junior Station Assistant if this was Shellharbour Station. He was told it was. He then asked "where is Shellharbour?", and was told it was about 6Km that way. Well, why didn't they build the Station there? "Because it's probably better being here next to the railway line!" Ahh, JSA's of the '80s, will we ever see their likes again?
David Hill then undertook to have the station called Shellharbour (Dunmore), because it is actually located in the suburb of Dunmore. When a brand new station was built 800m closer to Sydney in 2014 (at Shellharbour Road, still in the suburb of Dunmore), it was called Shellharbour Junction. The original Shellharbour station is now called just Dunmore, with it's original 1887 building.
Anyway, next clue is open to anyone who wants to have a try.