Joint will of spouses
Unlike a unilateral last will and testament, which the testator can revoke or modify at any time, a joint will between spouses contains mutual dispositions that bind the parties. Dispositions are considered “mutual” if they would presumably not have been made without the other party’s disposition. The dispositions may involve naming each other as heirs or naming the child of the marriage as the surviving spouse’s final heir (Berlin will).
While both spouses are alive, either may revoke his or her mutual dispositions. However, the revocation must be recorded by a notary and delivered to the other party. Once a spouse dies, the dispositions are generally binding on the surviving spouse, which means he or she can no longer change the order of succession. An exception is made, however, if you have expressly reserved the right to change the will.