It is important that all the different ways assets can pass down do not contradict one another, or an estate plan may not be effective.
A common problem that creates conflict was discussed recently. It began with the creation of instructions that the contents of a bank account should be divided between three children. However, that provision could be overridden, if that bank account says it should be transferred on death to only one of the children, according to the NWI Times in "Estate Planning: Catching up on reader's questions."
This is actually a common problem. When people open bank accounts, they make them transferable on death at the bank's urging. Then they do something different with the account, when they create their will. This leads to problems. The person who gets the bank account through the transfer on death, is under no legal obligation to heed the wishes stated in the will.
An estate planning attorney can advise you in a periodic review of your estate plan to avoid any conflicts.
Reference: NWI Times (May 27, 2018) "Estate Planning: Catching up on reader's questions."