The order you put schools on on the CAF must be your genuine order of preference. Only you and your LA know what order you put schools in - each school just gets told that you want a place there and assesses the request in the light of their admission criteria.
e.g You rank schools A, B, C on the form but in fact you really most want a place at B. Child meets criteria for A and B and the schools inform the LA. LA allocates a place at school A, because you put them first on your CAF. This is all they have to go on; as others have commented, the LA is not psychic (and a school no longer gets the opportunity to discriminate against your child because it is not your first choice