The proposal I shall be making is that if, as a requirement of the flight (no matter by whom - ANO, Club or whoever), there is an authorised instuctor on board (i.e. FI or CRI/SPA such as a PFA coach), than that person will be PIC. The other pilot will be Pu/t.
Because its tosh! If the instructor was giving instruction then yes I agree.
If the person taking the flight holds the relevant licence then they are P1, they are there as a safety pilot as a requirement of the clubs flying order book/insurance/will of god/etc then the FI is SNY as regards how logging.
As stated previously, nothing stops P1 swapping in mid flight.
There are occasions also when the FI would also not warrant P1 for the whole flight. I.E. If someone from a club up North is completely a XC check then why should the FI log P1 for the whole flight when most of it is across the UK?
J.