By today you probably found Albert Einstein's (born Ulm, Wuerttemberg) ancestors in (Bad) Buchau, Wuerttemberg. Weil's were numerous in all Jewish communities in South Germany. What I can add is my Feitel-connection. My earliest Weil, Seckel, lived in Ellerstadt, Palatinate (now part of Wachenheim/Weinstrasse) and died there before 1798. His wife Regina Rachel was the daughter of an Enzel Feitel from Friedelsheim. So I would expect that the name Feit(el), when reoccuring in my Weil family, actually originates in a maternal line (which might connect to earlier Weils).