The guest record
One guest is one row across every hotel. A shared email is not a person, and the guest who is already booked is not booked again.
Every guest, company and agent the hotels have ever sold to is one record, and a stay in Goa shows up when the same person books Delhi. The record is written by the front desk and read by the CRM; nothing is imported.
A shared address is not a person
OTAs send their own relay address on every booking. A guest arrived once as somebody else because two bookings shared an address — so the system no longer matches people on an email alone. The name, the phone and the address together make a person; an address by itself makes nothing.
The guest who is already booked
Take a booking by hand for a guest who already has one for the same night — because the channel's booking was waiting for a room and could not be seen — and the system says so before it writes a second stay. One question, one sentence, and the double booking that the audit would have no-showed never happens.
Putting the stay in another guest's name
A guest who leaves early asks for the bill in a colleague's name. The administrator can put the stay in another person's name at any point — in house, departed, billed — and the log says who, when and from where. Correcting a guest's own name is a different thing and renames the record everywhere; changing which person a stay belongs to is this.
What is kept
Identification, nationality, preferences, GSTIN for B2B invoicing, and a do-not-email that is absolute.