I have discovered through DNA that my father, isn't. How can I change to the correct name?
FamilySearch Family Tree does not restrict you from adding another person as Biological Type of Relation for Father - and changing the current to Guardianship/Step.
You can do this by viewing your current father in the Tree. Then scroll down to where it shows you as a child and select the Parent-Child Relationship icon.
Then you can Add/change the Relationship Type.
Then add Father with Biological Relationship Type.
Jane Roland You can also leave the man who raised you as a father connected to the family group, but change your relationship to Step.