@gaylea1 I don't think it's ever too late to show your gratitude. I was told to wait a while until their grief was not as raw, and I did. I too knew nothing before writing a letter, my surgeon wouldn't even tell me the gender of my donor! I wrote to them and received a letter back, almost a year after my letter. They were very open in their letter, signing their names and telling me the name of their daughter.
How is your situation different? Maybe we can offer some suggestions if we knew more. If I can find the guideline given to me by the local UNOS group I will scan it in and attach it if that would help you. That is, if I can find it.
JK