I was recently at the CAA waiting for a licence renewal, when an unhappy applicant was sent away to correct his logbook as he had claimed P1/s for a number of hours on a single crew plane when he was not undergoing a test for the issue or renewal of a licence or rating.
Going from a 172 to a PA28 is not a type conversion requiring an official test as they are both SEP however much sense it may be to have some training.