At the bottom of the Edit Spec page within Standards folders, you will see a listed of the corresponding linked Spec Instances. Select only those Spec Instances that you want updated and click the "Submit" button.
Behind the scenes, we first create a copy of your original Spec before any edits are applied; the unselected Spec Instances will be connected to the Spec-Copy and the selected Spec Instances will be connected to the original Spec with your newest edits.
Warning regarding Nested Specs
You probably did not realize this, but when adding/editing Nested Specs, information saves immediately (even without clicking the "Submit" button). So, for example, if you have three (3) Spec Instances and you are trying to add/edit Nested Specs for 2 of 3 Spec Instances, you need to modify your workflow slightly.
You'll need to first select the 2 of 3 Spec Instances at the bottom of the page and click the "Submit" button. Then, go to edit the Spec-Copy and add/edit Nested Specs within the Spec-Copy.