Since greed works in people, it takes no time to change. Especially money-related matters can cause a quick reaction, even a trusted person in one's family can do this. I don't think it's better to tell about the money. And if someone needs to be informed then only he can be informed that he has money but to reveal how much money he has can create a different reaction. Even if you don't trust an outsider, you must trust a member of the family. But you have to take responsibility for your own financial security or else it will be risky. As much security as possible regarding crypto assets that will be better for the assets holder.
Money is very powerful and it can divide a very close family brother against brother, keep your seed phrase to yourself and your mouth shut concerning anything that has to do with your fund or wallet. It's just that everything has gone south if not the safest people to disclose such an information to is your family but since money can change the character of someone, your financial security is your responsibility alone so for me, I'd rather back up my seed phrase instead of disclosing it to a family member in the off chance that I forget or misplace it.