Maybe if you have a very good friend you can trust him/her, while your nephews grow up.
Maybe friends are good options. But dont you think that it will be better if you trust a member of your family? Like your wife or your kids or even your parents. It is not very hard to teach them about bitcoin and the cryptocurrency
I think a real friend is someone you can trust, however, there are many things that can happen. The friendship is beautiful, but it often comes with the traitor. This betrayal hurts you more than anything, so do not choose the wrong person.