u take one treeview and one combobox and textbox and 3 buttons . one button name is add parentnode ,second button name is addchildnode and third button name is deletenode button.
if u enter the text in textbox .we click the parent node or child node. that text will be added into the treeview control and also saves in the combobox. like that if u delete the any parent node that time delete the parent and under child nodes and also at the same time removes the parentnode and uder childnodes removes the combobox.