To be or Possessive Case Sam's Bob's granddad.
Lilly's John's uncle.
• Tom's father
.
Tom's a father.
• He's happy
Liz's uncle's a doctor.
• Liz's uncle's doctor​

Sam's (to be) Bob's (possessive case) grandad

Lilly's  (to be) John's (possessive case) uncle

Tom's father (possessive case)

Tom's a father  (to be)

he's happy  (to be)

Liz's  (possessive case) uncle's  (to be) a doctor

Liz's  (to be) uncle's  (possessive case) doctor