What is a better way of saying "two people have worked on their stories together"? Here's an example of a situation in which this phrase would come up:
A witness in a trial is suspected to have "worked on his story together with the defendant" and therefore, he is likely to be untruthful when answering questions. In this example, the witness is someone who would not benefit by lying other than getting the defendant off the hook. Someone like a family member.