Thomas Ryan's 1911 HISTORY OF OUTAGAMIE COUNTY contains (on page 933) a one-page biography of DWIGHT W. DEAN, including information about his parents, children, and his contributions to the early cheese industry in the area. Among other details, this summary indicates that he came to Appleton from Dale in June, 1893, and had 3children in addition to the ones you listed. (These three all died in infancy).
The summary also tells of his departure from New York and his 1879 arrival in Waupaca County, where he started his first cheese factory.His wife Helen (shown as "Helene" Wilson) was from Waupaca County.I checkedWare's 1917 STANDARD HISTORY OF WAUPACA COUNTY, but unfortunately, there is no mention of him in those volumes.
If you don't have a copy of this summary (and can't access this volume where you live), send me an individual e-mail message with your mailing address and I'll be glad to send you a copy.