I have to reselect the path layer to add
Paths are not Layers.
Why Selections anyway, why not change the subPathItems’ individual settings?
This is expected behavior. You often want the path deselected as having the path selected after making the selection may mess up the next operation, such as move, copy, etc. I think it would be more of a nuisance to have to deselect the path every time I make a selection.