What she means is that her child is partly of Hispanic descent and the names they've chosen do not reflect any Hispanic heritage. Instead, the names they've chosen are anglo-European names (of Gaelic and French origin). So now she is second guessing if they should incorporate the child's own ethnicity into his name. For example: Duncan Javier could become Duncan Javiero, Aiden Montaine could become Aiden Montae, and Seamus Perrin could become Seamus Pedro.
I think I got all that correct!
My two cents: If it is very similar, I would consider the Hispanic middle name (like the first two examples I gave above). It provides a strong connection to his adoptive family (branches on his tree) as well as his heritage (the roots). What a great way to blend the two together-- a task you hope to accomplish not only in his name, but his life. But I wouldn't go out of your way to create a highly ethnic name that is distinctively different from the rest of your family, either. Lastly, I would check the meaning of the name. I wouldn't suggest naming your hispanic child something like "fair-skinned" or "red-haired" (unless those attributes apply).