This little tidbit actually came as a suggestion from a colleague using OpenText at PennState University [http://www.psu.edu].
Quick preface note, when requesting that an editor enter a URL for a link, keep in mind that you do NOT have to use an anchor element for this. Standard Text Fields can be formatted to accept different values, including dates, emails, and best of all, URLs. This means the content entered by the editor will be rejected unless it contains an http:// and is void of spaces.
For my specific project, I was connecting images with corresponding URLs. For instance, I would have a picture of a professor conducting experiments and a corresponding link to a blog article explaining his latest research. There were multiple images with multiple corresponding links. The images and URLs needed to be connected in someway to ensure that the correct link was matched with the correct image.
Enter "Child element of".
I created the placeholder for the first image: img_main1
I created the corresponding link using a standard text field: stf_main1
While creating the stf_main1URL, I specified the "Type of field" as "URL". Then, on the same panel, under SmartEdit Properties -> "Child element of", I choose img_main1 from the dropdown menu.

Inside the template I placed one red dot for the img_main1:
<p><a href="<%stf_main1URL%>"><!IoRedDot_img_main1><%img_main1%></a></p>
SmartEdit users see one red dot for the image, but when they click on the red dot, both fields (img and stf) appear:
This idea was the spring board for many more "custom" red dots that I use on the site. It's proved to be a handy grouping tool, in place of the broad "Edit Elements via Form" and the messy look of more than 5 red dots on one editable page. So far, it appears there is no limit to the number of Child Elements a parent element can contain.
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