To do this, you are going to need to sit down with your estate planning attorney, since you will need expertise with someone who knows estate law well.
You may also need to get some advice from a divorce lawyer in the state where your child or grandchild lives, in order to understand marital property laws and divorce in that state. Your estate planning attorney can also look those laws up and get advice as needed.
A marriage is a good thing to celebrate but it might be wise to consider the consequences to the estate plan, if things turn out badly.