How do I appropriately acknowledge "Happy Birthday" on the Facebook page of someone who has died?

[Adamismyname]

I just was looking at my Facebook birthday calendar and Monday is the birthday of a man I know (friend of my grandfather's) who died last summer. I don't want to write "Happy Birthday Bill" since he is dead but I would want to acknowledge something respectful for his family to see as his grandkids set him up with Facebook when he was home with colon cancer. How would I appropriately word it as he still has an account set up as if he were alive and at Christmas I saw a few people had written things like "thinking of you".

[Ashley Kim]

well i had a friend who died last year and i wrote happy birthday. thinking of you always. he shares the same birthday as me so i felt very depressed. just dont say it like he is still alive. say something in between