We have embedding cartridge In New application wizard on second wizard page. We allow user to add a new embeddable cartridge by clicking on button Add (it opens shell) and select a embeddable cartridge from the list of available (not yet embedded) cartridges in the shell. This shell contains also Deselect all which is not useful on this place (only use case is if user want to add new cartridges, he click on more cartridges and then he decide to undo it - this is not useful I think).

But the real improvement comes on the second wizard page in Embeddable cartridges section. There is a button Add (mentioned earlier) and a button Remove. There could be also button Remove All - to remove all selected embedded cartridges from the list of desired embeddable cartridges.