Which sentence correctly forms the possessive noun(s)?

Amber's and Lucas's trainers were both gold medal winners.
Amber's and Lucas' trainers were both gold medal winners.
Amber's and Lucases trainers were both gold medal winners.
Ambers and Lucas' trainers were both gold medal winners.

Question

Which sentence correctly forms the possessive noun(s)?

Amber's and Lucas's trainers were both gold medal winners.
Amber's and Lucas' trainers were both gold medal winners.
Amber's and Lucases trainers were both gold medal winners. 
Ambers and Lucas' trainers were both gold medal winners.

anonymous · Answer

@petiteme

petiteme · Answer

Amber's and Lucas' trainers were both gold medal winners.

anonymous · Answer

Was just about to type that....