George Sinclair b: 1887 (1910 Census Richardson Co age 23) Married: Catherine S. Schulenberg b: 1890 (1910 Census age 20)
Parents of Catherine: Joseph Schulenberg 11-8-1852 Erie Co, NY 12-10-1899 Falls City parents: John Schulenberg b: @ 1827 Prussia d: 12-19-1891 buried: OKC, OK - Immaculate Conception Cem Barbara Walter @1842 Alsace-Lorraine d: 1901 Married: New York children: John C.1854 Joseph 11-8-1852 Matthias 7-1-1856 sp: Caroline Portrey wife of Joseph Schulenberg: Johanna B. Sheehan 7-2-1865 Douro1910 Census: age 44 d: 12-17-1943 Falls City Married: 9-15-1883 Falls City Children: (Census for Richardson Co.) Vera R. Schulenberg 1885(1910 Census age 25) Paul S. Schulenberg 1888(1910 Census age 22) sp: Mary E. Catherine S. Sch... 1890(1910 Census age 20) Herbert L. Sch....1899(1910 Census age 11)
Johanna B. Sheehan 1865-1943 d/o Patrick D. Sheehan 1835-1917 Catherine McCullough Colliton 1840-1919 both buried: Lockridge, OK - St. Patrick Cem
g-parents of Johanna B. Sheehan: Cornelius Sheehan 1804-Hannah O'Brien 1807
This is all I was able to find on the Sinclair - Schulenberg family - some of this was on the Census for Richardson Co.
Not sure if this is the same Sinclair you mentioned in your info seeking statement - but its worth the try.