When I was on the 777, there was only one CA and one PIC (the CA). When he was sleeping in the back for 7 hours, he was still the PIC. He signed for the plane. We use three FO's. I was SIC, or TIC, or FIC; as assigned that trip. I logged the whole trip block in to out as SIC. I'm not creating new columns for third or fourth in command. It's my log book, so who cares. I'm not building time, so who cares. My company keeps track of duty time and landings for currency. I always had to go to the sim every 90 days anyway. The regs say little about how to log time and you only need to prove time for certificates, ratings, and currency. This discussion is about as important as not logging your long taxi times. I sat waiting for a gate today for 30 minutes; should I log it?
I keep track of my block times for pay and log that same number. It easy that way.