I believe I may have information for you. Southard Coolidge was born Feb 18, 1831 in Pottsdam NY. His children are:
William 1854 Laura 1856 Charles 1858 Vorley 1860 Nellia 1862 Frederick 1864 Ida M 1870
My FIL is related to Ida M. who was born in April of 1870 in Wisconsin. She married Herrison Sherman Milner and lived in both Idaho and Washington. As far as I can tell Southard moved from NY to Wisconsin.
Please let me know if this helps or if you have more information you can share. Cherene