Regarding « Leon Hu under "Departure Contact Name" and  Jacob So under "Accompanied by Name. ».
Hu and So are most certainly short for family names.
My hunch is that they are abbreviated because they refer to names mentioned in the same document. 

I suggest you search for a person named Jacob Soxxx who crossed the border at the same place and date. Chances are that you will find the complete name of « So » and that « Hu » might be referred under his full name as the departure contact of « So ».
If possible, scroll the border crossing documents in both directions, starting from your great-aunt Sarah. 

Daniel Ewenczyk
Paris, France

Researching: Ewenczyk, Evenchik (Minsk), Receptor, Retsepter (Luboml).