How to leave inheritance in Bitcoins to people who will not, or cannot, learn about bitcoin?

I have a problem. I need to leave to my mother and son what I have accumulated in bitcoins. But my son is a child, my mother is already elderly and has mobility difficulties. My wife passed away and I only have one relative to help her, but I can't trust that person to the point of handing over possession of the private keys to my wallet. I currently have most of my coins in a 3from5 multisig wallet with trezor/seedsigner/electrum as cosigners in the sparrow wallet.