Hy,
The simplest way would be to count 1 T/O and 1 LDG for each PIC entry (line) on your logbook.
A logbook is personnal, if this column doesn't exists you can creat it.
I knew some guys who were totalizing their pax.... Ihih
As mentioned above the aim is to justify your 90 days and night time T/O...
Do not buy a new logbook; it will make your work even harder (chasing Capt Names, signatures, stamps etc..