If you are left out of someone’s will there are two realistic courses of legal action. You can try to claim that the will is invalid. This is only going to be a viable course of action if, by invalidating the will, you stand to receive something from...
A will expresses the final wishes of the deceased person and it is commonly thought that a will is irrevocable after death. However, provided everyone agrees, it is normally possible to vary a will provided that the application is made within two years of the death.
A Deed of Family Arrangement, or DFA, (also known as a Deed of Variation) is a legal document which can be used to 'rewrite' provisions of a will. While these were originally introduced to protect dependents from being unfairly deprived, they are now mainly used to reduce Inheritance Tax.
To be effective, a DFA must be made in writing and signed by all of the beneficiaries who would lose entitlement to the affected part of the deceased person’s estate. If this affects any person under age eighteen, it may require the formal approval of the court.