The lego movie is very effective to appeal to a family because it relates to a variety of people of different ages.
It appeals to different ages through the different characters on the poster, there are different superheros that have been combined with the Lego characters this will engage older people as they saw these characters as they grew up and will want to see a different version of them now.
By the expression in Emmit's face shows us that its going to be an exciting movie, it also has a comedic sense to it , showing us its going to be funny, this would appeal to younger people more. In the background there is big cranes and Doctor Business towering over them showing that there is a lot of action. In the poster there are many different characters which all have different facial expressions as they run away, this means each family member can relate to someone.
The poster also has a relatable aspect to it they have added in things to the poster to relate to people who build Lego, the Lego movie logo is made out of Lego showing us the brand and it is being held up by a crane which people who build lego might relate to. The crane also tells us that the movie will be about building or have something to do with it.
The creators made other posters with the separate characters on them this was done to attract different generations to the movie. Morgan Freeman is known mainly by an older generation as well as a few younger people. He has a very Holy look to him in the movie and the poster he almost looks like what most people envision God to look like, this could be good for Religious people as it may attract them. He is also a very wise man and seen as he knows everything, adults may relate to this.
The poster of WyldStyle would attract to girls as she is a very confident, sassy , young girl who has a lot of power. This would attract young girls as they might look up to her. The poster shows us she is standing on a train track and that there is a train coming from behind her which shows us there is going to be action and that she is apart of it. 
Chris Pratt is a very well known Actor which would attract some people towards the movie to see more of his work. I think teenagers and some adults would be able to relate as he is a character who makes a lot of mistakes in the movie and gets sad sometimes as he feels as if he is doing things wrong but also learning from mistakes, this could relate to teenagers. Although he has an everyday job which adults may relate to and relate to how he works, or reacts to things at work. 
Will Ferrell is an very famous and comedic actor that lots of different ages love, it shows us that the movie will be humorous as he is normally a very funny character in movies.
