Make sure you have a plan in place so your loved ones are set up for success and never be in this type of situation.
The Lord is your father's strength, I pray he gets better in no time.
If you don't want to be bothered about your father taking risks on risky assets then help him convert the coins back to Bitcoin, unless you are very good just like your father when it comes to handling risky assets, I think you should be though because you are not a newbie on this forum.
I don't have to worry about what will happen to my crypto asset if something unexpected happens, my other half knows what to do and we have discussed this so many times already, I know how serious it is when it comes to life-threatening situations, we are not promised tomorrow like you said so we must always be prepared for any possibility.
I am very sure that many people choose crypto investment because of its hidden nature, where I come from there are many family feuds and trust issues everywhere, some people won't even dare to leave valuable things in the reach of their families, having valuable crypto is like knowing you are worth millions without anyone knowing.