Make the selected item the Group Master. Moving this item causes the whole group to be selected, similar to a Tight Group. However, other items in the group can be moved independently.
Shortcuts
Toolbar: 
Default Keys: None
Default Menu: Context menu
Command: Set Group Master Item
Locating this option
Available from: Context menu menu > Set Group Master Item option
How to set the Master Item for a Group
Firstly, you need to create a group of items. The group should not be a tight group.
Select a member of a group and then choose Set Group Master Item from the shortcut menu. The selected item becomes the master item, any previous master item is no longer the master.
The master item of a group can be found using the Find dialog and selecting Groups from the find category list. Select the group name you wish to find and the first item will be selected (or highlighted, you have the choice). If the group has a master item, it will always be selected first.