Grandfather's estate has not been divided, and now several of his children have also died. How do we resolve this?

This is called a layered estate, and it is resolved in the order of the deaths, one by one. First, determine grandfather's heirs on the day he died. A child who was alive then still receives his share even though he died later, and that share then passes to his own heirs. The longer it is delayed, the more heirs are involved and the harder it is to reach agreement. Appoint a trusted family representative to collect the death certificate for each layer and draw up a complete family tree. Then ask the estate officer the best way to apply for each of those deaths. This step prevents land from lying ownerless for years more. See managing an estate.