Oh shut up. A witness statement is a formal document of your OWN account of what took place and what you saw. It must not include opinions and must not be copied from someone elses .
Call yourself a lawyer. I know because i have written one.
Police are allowed to put opinion in their statements. Police like others are allowed to confer with others before giving a statement. Police can discuss what they did and observed before writing statements. They are often asked to include specific things in their statements not to simply write up anythign and everything.
Police try to prevent suspects from conferring with their suspected partners in crime to try to prevent them from making up join stories perfectly but sometimes they make it up before police get to them. police ask people things verbally and they get them to write down the parts that are pertinent, they make sure the key things are included. They don't want them leaving out some key thing they said verbally.
Police give testimony in court and use their notes for recollection purposes their statements and notes are not substitutes. The defense gets to question any police officers they want to and to cross examine any the prosecution calls to testify.
Statements exist for the benefit of those handling the investigation and those handling the decision to prosecute.