Can anyone show how the ANO (or any other legislation) in the UK allows PIC to change from one to another during flight?
I don't know how it works legally (I personally believe it's legal and have actually done this a few times already), but I would offer that it *might* be a bad idea, depending on the circumstances.
Suppose two pilots go flying. They agree to split the PIC time and (thus) the costs. Pilot A is happily acting out his duty as commander and flies the aircraft within his personal and legal limitations. When handover time comes, B finds that the situation is actually well outside his personal comfort zone and/or his legal limitations. In other words, he finds himself painted in a corner by A. So what do you do?
It's probably the kind of discussion that you'd like to have on an internet forum or a flying club bar somewhere, but not in the air.