Glad to hear that you managed to get it all sorted out in time!
I can't see that the idea of 'changing PIC twice during the flight' would be acceptable - how would you prove that you actually flew an hour of flight training?
Anyway, now that you're on the new scheme, you merely need to have accumulated a minimum total of 60 min flight training within the 2 years before the validity expiry date - you can do it at any time and it does NOT need to be completed in a single flight.