Name and date of birth
Edit: Also Chris Smith is still a very limited sales opportunity compared to everyone. Plus Chris would be going alone assuming their partners name was not listed correctly or partners name didn’t have a ticket matching that too.
Hamilton already does something similar with having to present your ID plus the credit/debit card used for booking and the names must match. See https://www.ticketmaster.co.uk/hamilton/terms.html
The flaw in Hamilton is it’s only the name of the payer, but if multiple seats in one booking, those additional seats could still be on sold so long as the scalper escorts them into the theatre.
Solved by requiring names and dob for all ticket holders. No changes allowed. Mistakes (wrong name or dob) must be refunded and tickets back to lottery.