A note on the two Yavner lines from Lithuania, David and Moshemendel.
I noticed that David had a son Max, b. 1889 or so.I find that interesting.My great-grandfather Moshemendel Yavner died 1879 in Lithuania.Thereafter all his sons, Barney, Phillip, William, Louis, and Jack emigrated to NY and all (except Jack) named a son Max after him.Jack was a baby when his father died and did not know him.
It was customary not to name a child after an esteemed person, but only after the person died.It was considered bad luck to name the child if the older person was still alive.So, it seems possible that David was a brother or nephew of Moshemendel.
Is there any record of your Max Yavner's Hebrew name?Was it Moshe, or Moshemendel?The latter is actually a "Yiddish" name, I am informed.
I don't suppose your family has any memory of visiting Yavners in NY or even PA?