I'm not sure, but if you use Tree.selectedItem (instead of selectedIndex) property of tree you should set an object in dataProvider. So if you add it to dataProveder you should change dataProvider and selectedItem for your tree.
myTree.selectedItem = project.trackedItem;
Thanks all it helps.
Using the tree's expandItem function as well as tracking the new item that has been inserted into the tree, i was able to do have the newly inserted item selected.
I call on first expandItem passing the parent node - then set the data provider's selectedItem to the newly added item, which I have a pointer to.