Is it possible to use one AD780 to be the ref voltage of 16 AD977A for +-10V
It will cause problems. For AD977A, there is a current from AD780 to R3IN (See
circuit in fig 16a/16b, attached). Therefore AD977A will interfere others. You
should use AD8031/2 as the buffer in front of each AD977A. Or you can use AD977
since the connection is different.