According to family tradition, Sarah Sosha was the "daughter" of R' Israel of Pikov, but this is impossible since "Sarah Malka" daughter of R' Israel of Pikov tombstone was found in Berdichev (BTW, In the kvitel of Rabbi Chaim of Krosna, she is mentioned only as Malka). Therefore, it is impossible that he had a daughter named "Sarah Sosha". Apparently Sarah Sosha was R' Israel of Pikov's "granddaughter" (maybe the daughter of Shmul Shmelke who was named "Sarah" and born in 1801/2).
Today, the word נכדה usually means granddaughter. However, in the past it could also mean great granddaughter, or even descendant. Therefore, maybe the mentioned family tradition referred to Sara the נכדה of R' Levi Itzhak, through his son Israel, but actually meant R' Levi Itzhak's great granddaughter (and not granddaughter).