Check after the chicken cooks for tem mins. It should be a little salty. Also, check for saltiness in the water, too. It should taste close to sea water. What she is making is pakki ghosht ka biriyani. You can check for salt after the chicken boils. If you are cooking kachi ghosht ka biriyani, then you need to be really careful as everything cooks in the dum.
How many you are making original hyderabad briyani i don't know. I think hyderabad briyani is famous everyone are making no one can do original nawab hyderabad briyani style its only thei style they only can do simple every one are telling hyderabad briyani..