If you are a single bitcoin investor, would you rather teach a trusted family member about Bitcoin than involve your personal lawyer. I ask this because I grew to understand that lawyers are good at handling confidential issues like Wills.
Why not both? Anyway, there is no absolute answer for this as this situation depends on a case-to-case basis especially regarding with your relationship with the family.
As a general rule, however, it is better to keep your BTCs to someone who is not related to your or to someone who is neutral regarding with your relationships. In this way, there will be the avoidance of any bias in the event that your estate will be divided upon your death (which necessarily includes your investments and BTCs).
On the other hand, if you have a good relationship with your family members, then you can entrust its safekeeping and investment to the person to your liking. You may also give them all the wallet passwords, seed phrases, etc. and that person will necessary reap the price of your investments.