On event 'Refreshed', you can also change or reorganize any legend item (as you did for removing).
A LegendItemViewModel has 3 main properties that you can change:
- Label (that you can change to your alias)
- ImageSource
- Description (used in tooltip)
Concerning the removal of the group layer node, the legend control has 2 built-ins mode : "Tree" and "Flat".
With the flat mode (LayerItemsMode="Flat"), the group layers are not shown, so it might be what you need.
For other specific cases, you need either to template the control or to change the layer tree by code in event 'Refreshed'.