[foxylad]

Make the passwords one character longer than what is noted in the book? Only you know the character and where it is added.

For bank cards with fixed lengths, increment/decrement the nth character, swap two characters, or do a circular shift.

[dredmorbius]

Or an arbitrary number of characters. If you know the additional six alphanumeric characters added, that's another 14 million combinations to test.

Or 2FA, or ....