It sounds like the house is still in the name of the disponer to your father and uncle, ie that the house was not actually registered in your father and uncles names. And if your uncle was the legal per rep, a second grant must be extracted to the original disponers estate. A grant will still also have to be extracted to uncles estate
If the house had been put in their joint names, this would not need to be done. However a grant would still have to be extracted to uncles estate.