I am also looking for Yanke/Jahnke. My ancestor was named Gottlieb. His parents were Gottlieb Jahnke and Eva Williegalla.
Gottlieb(Jr.) was born in or near Posan. There is a reference in his obit to Millerslav, but there is no such town.
My Yanke's settled in Indiana. If you run across any of those names please let me know.