Sorry to hear that, I wish your dad a speedy recovery.
I don't trust even my own mother when it comes to money and I'm not leaving anything to anyone, if I die, crypto I hold will be gone forever. To each his own.
I'm a selfish bastard and I'm happy with that

The most important thing I've learned in life is to trust no one, especially your family as they are the first to abuse the trust.
Seen too many people getting screwed by own family, not going to be one of them.
Ask yourself, what is more probable - dying today/tomorrow or getting screwed by some family member you thought you can trust with big money.
If you already have some deadly sickness then you may think to share your wealth, other than that I think you are just increasing the chances of getting robbed.

I know how hard it is trust to someone when it relates to money, but you should at least have a special someone you can highly trust with your crypto assets when the otherwise happens.
I don't think, it's the best idea to have your crypto assets lost forever than your family member or close friend to have them. We are not praying for something bad to happen, but we should at least get ourselves prepared for the worst before it takes us by surprise that we don't have anything in store for families to take off.
However, since you are having difficulties trusting anyone, why don't you try to find someone close to giving them your seed phrase; you will purposely remove the last word of your seed phrase only to give it to someone else. Like, Your mom will have the first to eleven words of your seed phrase, and a friend will have the 12th word. It will be revealed when the unexpected happens to you. That way you have saved yourself from the abuse of trust or being screwed up in the future.