It bears repeating: DO NOT CREATE NEW DUPLICATE PROFILES.
You can edit these orphaned profiles, but changing the LNAB should not be your first edit -- and it may not be appropriate at all. Start by improving the profiles. Add text and sources to the profiles to document the details that you have about these people.
Look at the primary records to see how each person's name was spelled at baptism, marriage, on census records, in wills, on their gravestone, etc. Chances are good that one person's name was spelled different ways at different times -- and sometimes different ways in the same document. Record all of those spellings in the profile. The LNAB for each individual should be the name that particular person was called by at or near their birth. We should not impose our modern ideas of correct spelling on our ancestors. Thus, for example, if the birth record shows that a person was recorded as Brackin, that is the person's LNAB, even if they were called Bracken on their gravestone (the name on the gravestone is their Current Last Name).