Im sure if your neighbours discussed this with a solicitor they would be able to sort things out. My grandmother put a clause in her will stating that, she didnt want certain people to have any of her money, should they contest the will. She had to state why this was the case. their family could contest the will, but if their names are mentioned and reasons why, i presume it would be difficult to contest. At the end of the day, its your final wishes, which should be adhered to.