A friend of mine had an Egelhoff that married into his family. I did some research on that part of the family. I found that the name was spelled Egelhoff and Eglehoff in the census, so be on the lookout for both. Also your William that was born in the early 1800's moved from Jersey Co to Montgomery Co IL for a time as well as some of his sons. Be sure to check there as well to blend your family together.
Debbi Geer