Your question is really confusing but let me try to answer it the best I can.
Let me start by mentioning that this is why I hate Facebook contact syncing. People (like myself) don't use their real info and when you sync data you end up with a mess in your address book. I personally would suggest that you don't do it that way. My contacts that I set up manually are waaaay more accurate than merging info from Facebook into my address book. It takes more work, but it's worth it.
To tag someone in Facebook you have to connect it to their Facebook account and use their Facebook name. You can tag photos with your own name but it won't link up to the person's FB account.
Also are you using the newest version of iPhoto? And are these photos that you are tagging being uploaded and shared from the iPhoto app itself? You can tag people in iPhoto and then upload the photo album from iPhoto and it will bring over all of the data for the people you tagged to FB. But like I said, you have to tag them using their FB name and not their real name for it to be able to link to their FB account.
As far as I know, there is no way to accomplish what you are trying to do at this point in time.