Apologies if the questions seem irrelevant, but I needed to make sure that he never had his name on the title deeds.
Beth, you are 100% correct if you say that you cannot give away that which you do not own. So, if the title deeds are in your mother's name, then the house is not his to give away. It, therefore, remains the property of your mother and whomever she decides must inherit it, will inherit it. If she does not draft a will, it will inherit in terms of the Intestate Succession Act.
Furthermore, both the fact that the suspensive conditions (the payment of the R 12,500.00) and the time lapse since the court order and the non-compliance with the court order, in my opinion, makes it impossible for whomever the executor of the estate is, to now come and try to enforce the court order by paying the R 12,500 and having the property transfered. The order has simply lapsed through the efflux of time.
The fact that he has lived there for about thirty years it would seem, would also not assist him, since he lived there with her permission (I assume).
So, the executor of his deceased estate would have now choice but to draw a line through the paragraph in the will where he leaves the house to whomever.
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