Issue with adding a new icon to an existing custom font set

Dear Support Team,

A few days ago, I uploaded a set of custom font icons under the title "LZN".
Today, I tried to add a new custom font icon to that same set. When I use the title "LZN" (to keep all the icons grouped), I receive an error message saying, "This icon is already installed".
However, if I upload it with a different title, such as "LZN2", it works, but this new icon is then separated from the original "LZN" group.

Is there a way to add this new icon to the existing "LZN" set, or merge the new icon into that group?

Thanks in advance for your help.
Best regards.