I realise it's a bit late now as anyone who sends them has probably already written them.
However ...
If you know someone who has lost a partner or a child, please acknowledge it in the card.
Our son died 2 years ago. He was 14. This year, we've received less cards than normal, which is fine, but not a single me of them mentions his name, or acknowledges him at all.
It hurts to see our family addressed with him there. I don't expect people to include him at the top, that would be weird, but a simple 'thinking of' or 'raising a glass to' would make all the difference.
Every bereaved parent I know finds it equally upsetting, but I'm not sure that other people realise that. I know the friends who have sent a card don't mean to be insensitive or unkind.
So this is my public service announcement to you all.