Never before...

[umpire99]

...have I seen something like this before. A5 commits her fifth foul. R reports the foul to the scorer. Upon being informed by the table that this is her fifth foul, R tells U so that he can let the coach know. U starts toward the bench, but notices that coach already has a sub at the table. He motions in the sub and FT's are administered. At the next dead ball, A5 is waiting at the table to enter the game. U motions her into the game and play resumes. After another dead ball, the opposing coach points out that A5 is a disqualified player. The officials get together and assess a technical foul for playing with disqualified player. The coach argues that he did not know that the player had fouled out because neither official told him. The officials get back together and take back the technical. How could this have been handled differently?