My grandma granted me one acre in a special warnty deed. Now she I trying to get a lawyer to split the land in half while I still pay all the taxes. This lawyer is know for doing back door deals how can I protect myself and acre.

If you have a deed for the property that lists you as the Buyer or Grantor, and if that deed has been recorded in the county clerk or county register's office, then the only way that property can be modified is if you sign the paperwork.

The only way I can see someone else making changes once you are the registered owner is if they forge your signature.

Well there is a possibility that Grandma can be proven unfit to have signed the deed or that you execrcised undue influence in convincing her to sign it.