How to load a newly made .umap file without changing the orignal built exe ?

Hi, I have already built a game with a map named A.umap, and send the exe to my user. But later my user want another map like B.umap, and I made the new map in UE editor.
I know if I build another exe it will work, but the truth is that I can’t change the original exe. Is there any method I can apply to load the B.umap file? Or, can I dynamically load a .umap file which doesn’t be packaged into the orignal exe?