Menachem Nachum Twersky, 1st Chernobyler - Mordechai Twersky of Kovno

I am trying to find Mordechai Twersky of Kovno. He had married Chaya Dora daughter of Eliezer Charash and his wife Dina Neviasky. He died before 1912. Dora came to the USA in 1912 with 2 sons. One was Efraim (who changed it to Phillip) and another son (unknown name). I am looking for 2 things: 1) How is Morechai related to the rest of the Twersky Dynasty? and 2) Who was Efraim's brother?
You can email me at dwittenberg@comcast.net