At my age, lots of people think that children should always be happy, capture being young at every moment possible and take every situation free spiritually.
So is it ok to be sad at a situation like this and is it still ok to capture something so serious and sad? Well I think it is, feel blessed that you still have the chance to hold your loved ones hand, and spend whatever time you've got with them laughing and smiling. Don't let it make you sad when seeing them think of it as a happy happy time because trust me , even if they don't show it like my grandpa sometimes doesn't, they have lit up inside!
You have just made someone close to your heart happy on their last days, smile it looks good on you