We’re in the middle of updating our wills, POAs, trust. House has been in already-existing trust – MIL had hers in trust and DH was able to sell without waiting for probate.
Once one of us dies we’ll have a family trust kick in for some of our assets. Terms will be that any withdrawals from that will need signatures from both sons as well as surviving spouse.
Medical POAs will include both sons (now 26 and 29), and we’ll set up living will and other documents to be as explicit about our wishes as possible. DH had to make / implement MIL’s wish to end nutrition and hydration at the end of her life, and we involved our sons. One of them took some more “are you absolutely sure” time than the other (it didn’t hold up the decision), but they both had the same sober, analytic, careful approach to the decision. We told them if they had to face something like this with one of us, to remember that their relationship was the most important consideration in the face of any ambiguity.