Becky Murtaugh is the second daughter of Jimmy and isn't seen much. She has only two lines in the whole movie
Becky can also sing very well. It is most likely that she (and the other Murtaughs) plays an instrument, seeing as Elliot plays the timpani at his school's orchestra. It is also likely that she's an overachiever like her siblings.
She is shown on her father's accomplishment video in the trophy room for winning "best all around athlete."
Becky Murtaugh is played by Melanie Tonello.