All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The inheritance should be divided after the death of the person, and this man has no right to disown his two sons or any other heir from the inheritance because even if they were non-Muslims in principle, they may become Muslims before his death, and so, they will deserve their right in the inheritance. It should also be noted that if they were Muslims in principle, then one should not hasten to rule that they are non-Muslims even if they have apparently committed a sin that takes them out of the fold of Islam because declaring a particular (Muslim) person out of the fold of Islam should meet some conditions while there are no impediments (which prevent from declaring him as such). We have already discussed this matter in Fataawa 91567 and 84943, so please refer to them.
On the other hand, the parents should be just between their children when gifting them as we clarified in Fataawa 119032 and 96941. However, if one of the children exerts himself to help his father and work with him, then the father can pay him according to what is customary in order to compensate him for his work, or that he should assign a salary for him, however, this should be within the norms in return for his efforts. If what he gives him in return for his efforts is beyond the norms, then this is favouring him in gift-giving; for more benefit, please refer to Fatwa 119967.
As regards the property that this man gave to his wife, if this was for a purpose other than making her its owner, like facilitating her to act on it when necessary, then the property still remains within the ownership of this man. However, if he had gifted the property to her in order to make her its real owner, and she possessed it before any impediment happens, like the husband becoming so sick that it is feared that he will die because of his sickness in general, then this is a valid gift unless the purpose of this gift was to harm the heirs and prevent them from their right, then the harm should be removed –as stated by the scholars –and the Prophet said: “There should be no harm nor reciprocal harm.” [Maalik]
Therefore, if there is an injustice, the father and that woman (his wife) should be advised in this regard. The help of some pious and righteous people should be sought about this hoping that Allaah would facilitate for them to solve the problem.
Allaah Knows best.