What a lovely gesture!!

I would definitely include it in your/their contracts. In relation to the sympathy card I would keep it solely as a sympathy card. If you wanted to you could put in a note, on a seperate piece of paper, that the fees have been waived.
If it were me I wouldn't want to read about the fees being waived everytime I read the cards.

Thank make sense?
Sorry, yeah, that's what I meant by I'd put a note in the card - I meant on a separate bit of paper