Hello Carolyn...Years ago - I had found a book Esler/Estler's of New York and New Jersey in the Morristown, NJ libray, & I think there I had read a woman, in the 1800's had added the "T". Wether or not this is true, most names were changed due to the sounding of it, especially when they arrive in America. I have seen the spelling of Estler, spelled Esler, which I believ is the orginal, Esseler, and once even Eslor, note the o. Estler, is a tough name to track unfortunately. As you may know, it is indeed German, but am unsure where in germany this family orginated.