If you are a parent of minor children, you should name a guardian for them in your estate plan. This person can step up and raise them if you die before the children reach the age of majority.
In most cases, your co-parent (whether they are your spouse or not) will assume this role. However, it is entirely possible that you may both die at the same time – especially if you are a couple and spend a lot of time traveling together. Remember, you are more likely to die in your car than on a plane flight overseas, in a skiing accident or at the hands of a random attacker.
Their capability to fulfill the role
When choosing whom to name as guardian, you’ll need someone who can do the job and is likely to be able to do the job until the children reach 18. Your aging mother might be great with your two-year-old right now, but you’ll need to consider if she will still be up to the job when the child is in their teens.
Maybe you have one sister and no other family. She is very deeply devoted her religion, to what you would consider an extreme level. Would you be happy for your kids to grow up this way? Or would you be better off finding a friend whose values more closely mirror your own?
Perhaps your friend shares your values but is always up to her eyeballs in work. Or she has the time but is married to someone who has made it clear he never wants kids.
There is a lot to weigh up when choosing a guardian. If you think you have found someone, consider seeking legal guidance to learn more about the legalities of the role and to formally document your decision in your estate plan in an enforceable way.