Add or remove selected objects to/from a specific(selected) group

Add or remove selected objects to/from a specific(selected) group: - There's no way to remove a selected object from a group without ungrouping all the members(destroying the group) and grouping again with the new object. If the group is a child of another group, the freed objects will get in the parent and there's no way to create a child group out of some objects of an entire group.
• We can't add an object to an entire group unless grouping the object and the group together that creates a new bigger group involving both, that is not the answer.