I would be careful about assuming this. If one of my friends left me a couple of words that I did not know the significance of, I'm not going to go around all their friends and family after they died and ask if anyone knows the significance of them. More likely I'll assume they were a password to something that is no longer needed now they are dead. Different if it's someone familiar with bitcoin, but with someone who has no idea what seed phrase are, your coins may end up irretrievable.
I understand your worries and it perfectly makes sense. However, in this case, they know the significance.
They know what I do and what I deal with. They are not tech-savvy and don't have interest in real bitcoining. But they know the money in their. It's basically in the family.