Don't forget my theory that Tommy was on a secret mission for the state department. Fighting by the side of Chiang Kai-shek against the Reds. Tommy eventually marrying Chang's daughter. See the lost adventure: "Charlie Chan in Taiwan". In order to maintain the fiction that Tommy is not undercover, that he is with his father solving cases Jimmy poses for a while as Tommy to maintain the fiction. Everyone plays along. As for Mrs.Chan she is in nearby LA helping to take care of the ill Frances and Iris Chan who have been both severely hurt in a car accident. They are both married and Mrs Chan has taken charge of both their households. One is a widow and the other's husband is overseas serving in the military. Mrs Chan is mentioned all the time by Charlie, just not "on screen" as the time of the Winter's Chans the ladies are well on the mend and the conversations concerning them are very mundane. Of course the "lost" case that takes place right at the tragedy mentions her all the time. It is the "lost" case: "Charlie Chan's Family" Needly to say the "accident" was no accident.
O yes, I forgot to mention all those hospital bills. Charlie retires and goes into private pratice to raise the needed cash to pay all those bills. Especially to pay for that "special operation" that saves Iris's life!