Hello Martin, 

At the moment this is a design limitation with the UltraLegends. You could create your own legend with the content/structure you desire. 

In Wpf the LegendBadgeTemplate makes it possible to modify the legends but in Windows Forms the is not available. 

You can suggest new product ideas for future versions (or vote for existing ones) at <https://ko.infragistics.com/community/ideas>.
Submitting your idea will allow you to communicate directly with our product management team, track the progress of your idea at any time, see how many votes it got, read comments from other developers in the community, and see if someone from the product team has additional questions for you.
Remember when submitting your idea to explain the context in which a feature would be used and why it is needed as well as anything that would prevent you from accomplishing this today. You can even add screenshots to build a stronger case. Remember that for your suggestion to be successful, you need other members of the community to vote for it.

Let me know if you have any questions.