Ability to isolate selection from within isolate mode

Would be really handy to be able to further isolate a selection from within isolation mode.

Example:

select a three objects.
press ‘/’ to isolate those objects
select 2 objects (whilst still in isolation mode)
press ‘/’ again to isolate the new selection

Result - blender goes back to the un-isolated mode with the initial 3 objects still selected, instead of isolating the objects selected in isolation mode.