Tom,
What kind of track are you using?
When I had my N and HO Scale Inglenook Sidings, I used Kato Unitrack with the built in magnet uncoupler. Otherwise just use Atlas, Peco, etc and place an aftermarket magnet on the parts of the 3 forks in the track that you want the cars to uncouple. The way it works is that you slow the consist down once the 2 coupled cars that you want to separate the load at is over the magnet. With the consist stationary, slowly pull the consist out of the siding (back in the direction that you came from) and the magnet will open the couplers and separate the cars. You then have the locomotive pull the rest of the consist away and off you go. No buttons to push or lever to pull like in O gauge.
Regards...
