Casting

Laura: Lesley

I choose Lesley is because she has a good understanding about the character of Laura: delicate, and lives in her own world. Laura is a weak and small character, and Lesley has a slim body type, as a result, she is suitable for the character.

Tom: Josh

I think Josh can be Tom. He can really act it like Tom, caring about his own future. However, he also cares about his sister. Josh is tall, and in order to illustrate the working place: warehouse. He is strong, and talented in literature. 

Amanda:  Gianna

I choose Gianna because she is playing Thenardier in the les miserable. The acting skill is significant, and she annotates the annoying of Thenardier, so I think she might be able to play Amanda as well.