Below, we've shared how Illustrator's Group Selection tool can be used to isolate individual objects from a larger group, or select sub-groups that are nestled in a group.
Accessing the Group Selection Tool
Located in the Tools panel (in a subfolder of the Direct Selection tool), the Group Selection tool allows you to retain your current grouping arrangements, while still being able to select objects with a click of the mouse.
Besides going into the Tools panel, you can press the A key to enable the Direct Selection tool, and then hold the Alt key (Option on Mac) to switch to the Group Selection tool. You'll should see a plus sign next to your mouse pointer when in this mode. When you release the Alt key, your cursor will change back to the Direct Selection tool.
Group Selection vs. Direct Selection
At a glance, it's hard to tell the difference between the Group Selection and Direct Selection tools, but there is one key distinction. With the Group Selection tool enabled, if you click on an object in a group, that object is selected. Clicking again will select the entire group where the object resides, and repeated clicks will select the sub-groups going up the chain, until you reach the main group (or nest).
When you have groups inside of groups, things get pretty complicated, but the Group Selection tool allows you to make precise edits without worrying about ruining the larger arrangement.
Other Uses for Group Selection
Finally, if you select an object with the Group Selection tool and move it to a new location (away from the group), it will still be considered part of the group. Dragging on the group with the regular Selection tool will move every object in the group, even if you used Group Selection to move an object to the opposite side of the page.