Tenants-in common and property deeds

My father-in-law recently died and in his Will he left his share of his house equally to his son and daughter as tenants-in-common. The other half of the house remains with his spouse. On checking with the Land Registry he made the tenants-in-common agreement in 2009 when the property was Leasehold. In 2011 he bought the Freehold to the property but the deeds did not take into account the tenants-in-common agreement and the deeds of the house now show the property in joint ownership with his wife. This means all of the property will go to his wife. This is clearly an oversight by the Solicitors who arranged the Freehold purchase. Does anyone know if my father-in-law's Will overrides the deeds of the property?