When my wife and I traveled to Germany many years ago, we used a hand drawn map from Rick Steeves from either Europe through the back door or Germany. My son is traveling there this summer but I can’t seem to find the map. Any help is appreciated.
The "white" church you probably mean is the WIES- ("meadow" in English) KIRCHE. You can find all 4 of these on the map below:
https://www.pension-info.de/bayern/fuessen/linderhof-oberammergau/index.html
Just wanted to mention that anyone visiting Neuschwanstein should also visit Hohenschwangua, essentially across the street. It is also pretty, its furnished, was actually lived in and the tour provides insight and context for the visit to Neuschwanstein. If your son needs to make a choice between the two, I highly advise just seeing the exterior of Neuschwanstein and the tour for Hohenschwangau.