Sample-and-Hold amplifier does 2 things :

1) Samples its input voltage level, AND
2) Holds or maintains it at its output terminal, for some time interval before which the voltage starts to drop.

So, If a D/A is feeding 8 S&H amps, then theoretically a control loop in a controller can writes each of 8x different values to the D/A while enabling each S&H to sample its inputs. This could be in a round-robin fashion.

If the loop can update all S&H amps within the time it takes 1 S&H to start loosing the voltage level, then wouldnt all S&H be holding their respective voltage levels, albeit with some, though acceptable, droops / jitters ?