Yes, I believe he is a brother for Frank.
Here are some basics for what I've found:
Information that is certain for my Grandfather Frank Clifford Fritz: born 29 Dec 1892 in Connecticut, and died 22 September 1964 in Colorado. The 1900 US census has him and a brother (Theodore born 1893) living with grandparents Christopher and Eva. I believe 1910 they are with a cousin or elder sister Lena (Ferriere). A NY passenger list for 1882 has Christopher and Eva with 2 children Clara and Theodore. It gets very confusing for me due to not knowing all children for Chris and Eva. Best I can tell they included Lena (B 1857), my unknown, Theodor (B 1873) and Clara (B 1876). I think there are more.
My search for birth records for Frank C. have not been successful. Other siblings for Frank: Edith (B 1888), Harry (B 1889), and Theodore (B 1893)
Through Ancestry.com DNA I have located a 2nd cousin from a brother of Frank (Harry 1889).