Dear Mary Ellen -
The only Cope I have in my database is a Mary Cope, b. 11 Nov 1863 in Easton, NY. She married on 22 Nov 1887 in Beekmantown, Clinton, NY to Frederick Herbert "Fred" Delano, b. 16 Jan 1861. I also show that they had one daughter, Gertrude, b. 23 Jul 1890.
My source for this information is "The Genealogy History and Alliances of the American House of Delano 1621 to 1899," compiled by Major Joel Andrew Delano, page 530.
Could this be the Cope daughter you are seeking?
I have some information on this Delano side of the family, but have not proved a connection as of yet, between them and the main trunk of the Delano clan. If I can be of further assistance, please let me know.