As an estate planning attorney, I am often confronted with a single parent who doesn’t want the other parent to obtain custody of their joint child(ren) upon my client’s death. Generally, unless there is good cause, one parent will usually not succeed in appointing someone other than the co-parent to be guardian.
Good cause may be found if the other parent has legally abandoned the child(ren) or is unfit as a parent. In the event that the other parent seeks custody upon your death, it is typically quite difficult to prove that parent is unfit absent significant issues such as alcohol or chemical abuse, a history of violent tendencies, or mental illness. As such, if you wish to name someone other than your co-parent as guardian for your child(ren,) you may wish to inform that person that this may lead to a custody contest.
I suggest that my clients not only insert language within their Will explaining their choice as guardian and also explaining why the other parent is a poor choice, but I also suggest preparing a letter in their own handwriting with similar language that shall be attached to the Will.
If you do not wish for your child(ren’s) other parent to gain custody, it is wise to discuss the matter with an experienced attorney that specializes in estate planning.