That may not suffice. My wife has a hyphen in her legal name, and even today, many companies' systems cannot deal with such a thing, or, worse, store it with the hyphen in one place and drop it in another, resulting in strange errors.
My girlfriend is from Spain and we very recently had our first child. Born in Spain.
My last name has a Norwegian “ø”.
My girlfriend has a Spanish “ñ” in her last name.
Here in Spain we decided to register the name of our child using simply “o” in place of “ø” for the last name that comes from me. For the last name that came from her we used “ñ”.
When we arrive in Norway we will register him there with the proper “ø” but here in Spain his name will remain having “o” in its place. Just like how I’ve taken to writing just “o” in place of “ø” in my name when ordering packages to be delivered to me here in Spain.
What we do about the “ñ” when registering him in Norway we will see. Depends on their computer systems. If they can enter “ñ” we will use that. If they can’t then he will have some replacement like maybe “n”. Either way, that part of his name will remain as “ñ” in Spain.