Most people do not like to face the concept of their own demise and yet, eventually everyone sees to. It is for this reason that so many people fail to set up living wills or trusts and thus, leave one big mess for their heirs and family members. It's hard to talk about such things with a senior member of our family, first, they might insist that you are trying to get at their assets or money, and two, because it's not very nice to think of someone's untimely demise.
Seniors are related to discuss it and so too are family members. If the subject comes up many older senior family members will just say "do not worry I put you in the will!" But be very careful of this because 25% of people with enough assets to warrant a will, end up dying with no will at all (intestate), and most of the people that talk about it a lot have no will; scary statistics. Most of those wills which are handwritten afterthoughts are not valid, and thus, probate becomes a legal mess.
It is imperative that you get your older seniors members to a qualified estate attorney and that they learn about trusts, living wills, powers of attorney, and while you are at it take them to a financial planner, one you can trust with strong referrals and get them set up so that their financial affairs do not become a burden or unworkable in their older age or after their death. If an older member of your family thinks that a stack of handwritten notes will suffice, steer them in the right direction, and do it right.