In my data base, I have an Alonzo H Stil(l)well, b 23 Apr 1852, Oyster Bay, Queens Co, NY. I don't have a wife listed for him. He is s/o Jeremiah Stillwell (26 Feb 1824, NY - ??) and Phebe Ann Wood (20 Dec 1830, NY - ??). He is in Oyster Bay, Queeens Co, NY, in 1860 census. Sibs of Alonzo are Anne Margaret, 1850; Osacr J, 1853; Catherine Amelia, 1857; Herbert H, 1861; Emily Rose, 1863; Georgianna, 1866; William, 1868; and John Wesley, 1872.
DOes this sound like your Alonzo?