If you do not hold title to your assets in a way that compliments your estate plan, then your estate can face difficulties.
Houses, cars, retirement accounts and bank accounts can all be owned and transferred outside of the control of your will. Daily Local News discusses this in "Asset titling can change the estate plan."
For example, you might own a home with your second wife as joint tenants with rights of survivorship. If you have a child from a previous marriage, you might want that child to get the house or your half of the ownership after you pass away. It does not matter if you express that in your will. When you pass away, the second wife will immediately become the sole owner of the home. That is how such joint ownership works.
This type of problem is avoidable. An estate planning attorney can work with you to create an estate plan that coordinates the proper titling of your assets to carry out your distribution objectives.
Reference: Daily Local News (June 26, 2018) "Asset titling can change the estate plan."