John Blomshield and history

My husband and I were going through some old family items we just received. Inside were letters from John Blomshield to Particia Marx (my husband¡¦s mother, maiden name Macon born in 1934) He signed them "your great uncle" He was living in the Philippines at the time. We also have found original sketches that he drew and old original negatives from some portraits he did. My husband was young when his mother died but he remembers her telling him that his great great uncle John was a famous artist and publisher who lived in New York. We found articles where he was in WWI and the traveled the world as an artist. He sketched and signed Earnest Hemingway¡¦s jacket to his book and was famous for doing a self portrait in the early 1900's. We would like to find if possible the letters my husband¡¦s mother (Patricia Marx ( maiden name Macon) wrote to her great uncle John Blomshield. We would like to also find out how he is related to us and his heritage. Any information would be helpful. Thanks ƒº