Your grandparents are walking libraries with no backup copy. Ask the questions while the doors are open.

Somebody who has lived a long time holds an enormous amount that exists nowhere else, including whole sections of your own family history. None of it is indexed and none of it comes out unprompted, because to them it is just ordinary knowledge about ordinary people. It goes when they go.

Prepare three real questions and ask them on your next visit. How they met, what the hardest year was, who you are named after and why. Write the answers down afterwards, even roughly, because you will not remember as well as you expect.