creating custom data model

I have an existing program that has separate variables for a DefaultTreeModel and a ListModel and someone suggested to me that I create my own class that combines those 2 data structures. The first question I have is should I implement the interfaces of TreeModel and ListModel, or should I extend DefaultTreeModel and implement ListModel so I don't have to recreate a lot of things from scratch?

The second question I have is if I don't extend DefaultTreeModel will I need to utilize methods such as addTreeModelListener() so that the components of my application that currently are alerted to the DefaultTreeModel changes (such as JTree) will still be alerted when my custom class is used instead? How would I go about making sure that a tree.reload(root) would still work if I do things from scratch?

thanks
Brandon
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