Yes, indeed, Charlie Chan's offspring HAVE helped him on his cases. The instance that you mention is a very good one. Also, in "Charlie Chan at the Race Track," Lee did much to assist his Pop. Please recall the droping of many notes to the various suspects by Lee, plus the great diversion he provided at the racetrack with the laundry truck filled with fireworks!
In other movies, Chan's kids have placed themselves in great danger to help their famous father. I think immediately of how Tommy was really roughed up by the diamond smuggling gang in "The Chinese Cat." Also, Lee faced grim consequences in "Charlie Chan at the Olympics."
There are more instances of how Charlie Chan's offspring gave him very real assistance in his cases. Does anyone else have any additional examples?