I don't know for sure, but doubt that Hiram Cummings is related to Sara Cummings Olmstead. The connection with Palmateers to Dutchess County is provocative, as Sarah Cummings who married Olmstead and Lease was my great-great-grandfather David Cummings' daughter. David also shows up in Branch County, MI, by 1834 according to the History of Branch County, but was born in Dutchess County, NY, circa 1797 went to Ontario, Canada as a child, married Martha Sutherland in Canada, and had there daughters Susannah and Sarah (named for his older sister Sarah, called Sally who married Silas Sutherland in 1803, and this couple also went to Canada.) I haven't found reference to Hiram in this line, but Horace is a possibility, William and Major are certainties.

Earle William Cummings