Originally Posted by turmalina

The reason they ask you to keep it hyphenated is because your ID documents are supposed to supersede everything. For most of my stuff here, I've only used one of my last names just out of consideration for how it is here but technically, my whole name with my maternal name IS my legal name.

However, in the app, there's a section where you can note the variations of your name you've used, so I strongly suggest you fill that in, specially if you have evidence where only one last name is present.