I discovered Paul Keshishian and Margaret Ferguson McClary's marriage record in the Rhode Island marriage record database on Ancestry.com. They were married on December 27, 1907 in Providence, Rhode Island by an Armenian priest. As the on-line record only had the names and dates, I went ahead and sent for the complete record from the Rhode Island State Archives. I was surprised to find quite a bit of information in this one document. Some of the information confirmed what I knew, and some things were new to me.
Paul Keshishian was the youngest child of Mariam Keshishian and I didn't know his father's name, but here it is on the marriage record as Elijah. The record shows that Paul was born in Armenia, was 28 years old and was a loom fixer. Margaret was 27 years old, divorced and had a daughter, Esther (who ended up married to Jake Zaillian, son of Arschalous Keshishian Zaillian, Paul's sister).
So, another piece of the puzzle. The only picture I have of Paul is in the large 5 generation picture of Mariam Keshishian's family, which I haven't been able to scan yet. Margaret is not in that picture, but their children Doris, Paul, Pearl, Albert and Ruth are sitting in the front row. By the second generation, all the Keshishian males were using the last name Kershaw. Henry Keshishian (1920-2005), son of Peter, was the last in the family to use the name.