jnnick412 on Family Tree Circles

I am looking for the family history for the PENKOFF / MCGIVEREN Family. My father-in-laws parents were Peter B. PENKOFF(b. 1908) and Mary McGIVEREN (1911-1975). I have no information on MARY MCGIVEREN except that after Peter's death she married Living STRINGHAM. Peter's father and mother were Baczkov PENKOFF (b. in Bela, Bulgaria?) and Nicolina (Edna) B. Unknown (b. 1883-?). I have reason to believe that her maiden name was possibly GEORGEOFF. Baczkov PENKOFF immigrated to the United States in 1906. He purchased a deed in Gregory, SD in 1914. Nicolina is soon after found in Lucas County, OH. She immigrated with her 4 sons, George B. PENKOFF, Peter B. PENKOFF, Penko PENKOFF in 1910. They had Charles B. PENKOFF in South Dakota in 1913.

I would like to know more about these families. If anyone can assist I would appreciate it.