Who is Puso and Motholeli from The Kalahari Typing School for Men and what is their importance?

Mma Ramotswe takes Puso in as her foster child. He is described as a frustrated, young man, who begins acting out by killing a small bird, and later telling Mr. Matekoni that he hates him. The matron of the orphan farm suggests the boy only needs added attention by Mr. Matekoni and this seems to help.

Motholeli is Mma Ramotswe's foster daughter. She is also Puso's sister. Motholeli needs to use a wheelchair, but she loves to work on engines and machines. Mr. Matekoni has promised that he will rig a ramp up for her, so he can teach her to work on engines at the Tlokweng Road Speedy Motor.