The friends of my daughters = ...

• My daughters friends'
• My daughter's friends
• My daughters' friends
• My daughters friend's

The car of James = ...

• James's car
• James' car
• Jame's car
• James car's

A school for girls = ...

• A girl's school
• A girls school
• A girl school's
• A girls' school

The brother of Amy and Louise = ...

• Amy's and Louise's brother
• Amy and Louise's brother
• Amy and Louise' brother
• Amy and Louise brothers'

The boyfriend of the friend of Naomi = ...

• Naomi's friend's boyfriend
• Naomi friends' boyfriend
• Naomi's friends' boyfriend
• Naomis friends boyfriend