Aelther is right about Facebook name sync overide
What I do is create a new contact with the same name as a fb contact and save it. I am then able to edit the FB contact, hopefully this answers your question.
Aelther has the answer! Thank you so much!
Some names in my contact sorted listing are changed (replaced) when Facebook records are joined to my existing contacts (Motorola's Droid together. This is a problem if you prefer a non-standard naming convention (Like using nicknames or ordering by Last Name, etc). For instance I put a leading character on some names (like a "D" before my doctors) so they all sort together in the master list.
If (like me) you want to use a name that is different from the name a person uses in Facelist, but you want to be linked, do what Aelther suggests...
1) After Facebook name has synchronized, separate the joined Google Contact from the Facebook Contact. This is done by Editting your contact... pressing Menu and selecting Separate.
2) Now Create a "New Contact" with the identical name as Facebook. Android will automatically join the with the Facebook contact.
3) You can then edit the contact to be the way you prefer.
Happy organizing those of you who are obsessive about this sort of thing (like me).