I read your posting with interest. Unfortunately it is about 2 years later. I certainly hope that you have the document you mentioned.
My grandfather, Abraham Reubenstone had a sister who married Maurice Exiner's father i.e. Maurice was his nephew (a well known fact in the family). I use a letter opener that belonged to him with an "x" on it that was given to me by my mom.
It would be quite a surprise if that document still existed.
Thanx,
LHT