When you are selecting elements and using the Filter tool in the Selection part of the Modify ribbon. You may not have noticed but there are some additional tools alongside the filter icon, Save, Load and Edit. These allow you to create selection sets for future use.
The Save selection, allows you to create a selection set of elements and give them a name so that you can retrieve it later, sort of like a group (without creating a group).
The Load selection allows you to load a previously saved selection set. Just select elements in your model and select the load icon and you will be able to select a previously created set from the Retrieve Filter dialogue box.
The Edit selection allows you to edit the elements in your selection set. You have the ability to add or Remove elements from your selection set.
You will notice that this tools works very similarly to the Group tools, without storing additional groups in your model and leaving all elements individually selectable.