You must respect the wishes of another player if they claim to not know your character. The point of a memory wipe is to give players and characters the opportunity for a fresh start without biases or baggage, and you must respect this.
Bob: “Hey, have we met?”
Sam: “Nah, you’re thinking of someone else.”
Bob cannot remember Sam, Sam doesn’t remember Bob, and they have a completely non-awkward first meeting.
This is easy. If you have relationships you wish to pre-handshake, just do it. It does not break any ‘memory wipe’ rules.