So I've got an object that has an observable collection. Most places I bind to this collection I only want the user to select a single item. But in one place I want the combobox to include an all items option.

Is the way to do this simply with xaml converter?

It seems like doing it in the view model would be a good idea, but it's really a lot dependency object goop to basically wire up an collection that is two objects deep for an on change event, where as the xaml converter just works.

But I always feel like xaml converters should be generic and reusable, where in this instance, the xaml converter would be more of a one off.

Of course the third option would be to create one off list for UI in the object that contains the standard observable collection. But this seems to be mixing the logic and presentation in a way that makes me uncomfortable.