How to add great-grand-father children in tree ?

[siddhesh-vartak98]

As the tree expands according to the root node, i.e., pedigree as relationship. However, if we have to add the father's father, it goes in the father array. But if we have to add the root's great-grandfather's children, i.e., the root's uncle grandpa, then how are we supposed to give the input?