Easy two-way linking of related items (suggestion)

I would love 2-way links too. My use case is for addresses, credit cards, mobile numbers, anything that changes over time. I currently can quite easily link an online account to say the credit card(s) registered with it. However, if those cards are compromised or expired, I'd love to be able to do a reverse lookup by going to the credit card item, and then finding all of the accounts that link back to it. That gives me a great TODO list of places I need to update. Rinse and repeat for changing phone and address when moving countries etc.