Hi Suzanne,
in addition to Vera's - as always - useful and knowledgeable information, I can add some bits:
Schellert belonged to the parish of Herrnneuses - at least that was the case in the 19th century. The church registers of Herrnneuses (Dekanat Neustadt a. d. Aisch) can be found here in Archion!
Rennhofen belonged to Emskirchen, Dekanat Neustadt a. d. Aisch, but the church registers are still kept in Emskirchen.
Dettendorf was part of the parish of Diespeck, again Dekanat Neustadt a. d. Aisch. The Diespeck registers are also still "at home", not in the Nuremberg Archive.
You can look up such facts in several 19th century "Statistics pf protestant parishes"; you will find the links to digitized versions here on the web site of the Nuremberg Archive:
http://www.archiv-elkb.de/kirchenbücher-0
It is, however, a bit tedious to look up small villages or hamlets because they are not listed in the index - only the parish towns/villages are to be found in the index in the books. But if you have an idea about the geographical situation of the villages, you can find even the smallest hamlets.
In the cases where I sent letters or e-mails to parishes, I always received friendly answers (not always prompt depending on the number of staff). They charge small fees for looking up entries and producing photocopies.
Perhaps it would be worth while to register to the mailing list for Franconia, Franken-L:
http://list.genealogy.net/mm/listinfo/franken-l. The language on the registration page can be switched to English, upper right corner. The mailing list is predominantly German, but many members read and write English as well.
Do you know about the local genealogical society for Franconia, the Gesellschaft für Familienforschung in Franken (GFF)?
http://www.gf-franken.de/
They don't have a mailing list of their own, but you would reach a lot of members via Franken-L.
The GFF produces a lot of books and especially their yearly issued DVD "Index Personarum" is extremely helpful.
Finding villages can be perhaps made easier with the BayernAtlas:
https://geoportal.bayern.de/bayerna...ng=de&topic=ba&bgLayer=atkis&catalogNodes=122
You can enter the place name in the field on top of the page, then you will get a list of finds to choose the most probable for your search. Top right (below "Bayerisches Staatsministerium ..." and the coat of arms) is another choice box where you can select the kind of map you would like to see. "Historische Karte" is very, very useful. It shows maps from the 19th century and you can zoom in - it is even possible to read house numbers in the towns!
Apart from finding villages, it is fascinating to see how the map has changed in roundabout 200 years ... small hamlets or isolated water mills being "swallowed up" by larger villages or towns. At least it is for me!
Regards
Susanne