Unknown 5 (Has been identified as Meyer Nadlin by my mother)
Unknown 6 (Has been identified as Joe Alber, Sam Hurwitz, Jennie & Sunny Albert by my mother)
Unknown 7 (Identified as Sidney Kottler by my mother)
On the back of unknown 1, there is some handwritten text in Russian. I've scanned that also. There is a date of 1/19/1902. Does this help?
Click Here to view the Russian text