I have a Bitcoin and a baby. Now I want a trust

Anyone set up a multi sig trust for something like this? I wantnto leave him a whole coin but not even sure what I should be thinking through and what boxes to check. I do have the Bitcoin and the baby. And suggestions on the others from anyone who has done somethingike this. There's a very real possibility that with my lifestyle I drop dead randomly. I trust those closest to me but don't trust their intelligence. How do to safeguard the future for them if you have some bags of coins?