I'm unsure about laws in other countries but the US allows you to leave property to whoever you please (even if they are not related, a charity, etc) so when a will is contested it is usually by someone who would get the property if the person died without a will. Because if contesting a will is successful it just gets thrown out. So it is usually biological or adopted children that contest it when something bullshit happens like their 90-year-old father leaves everything to his 20-year-old mistress. It seems strange that cousins would contest a will. In the US they would have to prove that not only was the will false, under duress, etc but they would also need to prove that the children were not really the children of the deceased or were legally disowned. A tough test indeed.
Exactly the same here, the will is paramount so if the property is willed in someone else's name or in the name of the charity, then the owner of the concerned possession will be the willed party. But if the will is silent and the property is personal, as in the property was solely under the ownership of the person who didn't make the will, that concerned property will automatically go to the next of kin, that is their spouse, children, dependent parents, at last siblings or their children etc in that specific order. If its willed, then everything goes to the person mentioned in the will unless it is contested.
When it comes to ancestral property, where the land has been under the joint ownership for generations, everyone in the family gets a piece of the ancestral property, once the property has been distributed, it becomes the respective owners personal property.
The thing is, disputes like this often breaks a family beyond reparation, especially when there is already bad blood between the parties involved.
Hope our dev. gets his due justice.