Togetherness

[JPIESIK]

     I've got a good instructor/client with a 1917 Sohmer 5ft 7in grand and 
     a '70s Baldwin SD-10 in her studio. She always wants the two tuned to 
     each other for obvious reasons, but I keep telling her that the best I 
     can do is have them both at the same pitch, and beyond that, the 
     pianos are just too different to tune exactly to each other. Then I 
     started thinking, maybe there is a compromise, in between, that would 
     allow me to do this. Is this possible? How would I determine the 
     compromise? She's rather picky - would she be happy with the result? 
     Where does the line get drawn as to which pianos (style, make, model, 
     size, etc.) can be exactly tuned to each other? I use an SAT, and 
     maybe I could play around with the FAC numbers to reach the 
     compromise.
     
     Thanks in advance,
     
     John Piesik, RPT
     Oceanside, CA