On this one there is no really good coherent answer that can be given. There are different parts of the law that deal with implied easements, reserved easements, express easements, easements by necessity, etc. Without seeing the documents on the court records, including deeds, any neighborhood covenants, plats, etc., a real answer is not possible. The best argument for having an agreement is to avoid questions, such as yours, in the future. With an agreement recorded on the deed records by the owners, everyone would know what was agreed and what rights and obligations go to each owner. I think on this one you are going to have to get with a real estate attorney who can look at all the documents and better advise you.
This answer is for general purposes only, and it does not create an attorney-client relationship.
If you need a survey of the property, you may want to start with a plat map. The closing attorneys for prior homeowners may have surveys in their files if needed (but not clear why it is needed, a survey can be ordered now). I will assume that you have verified that there is not a written agreement recorded on the plat or in any recorded documents in the real estate records.
All too often residential closing attorneys created vary basic "shared driveway agreements" if any at all. Since the driveway already exists, your rights and remedies are very constricted. A written agreement (well written) covers what maintenance is performed, when it is performed, how paid for and what happens if payment is not made or there is not agreement. My suggestion is that you should consult an attorney to draft a good legal form and to be sure it is properly executed and recorded.
Disclosure: This answer and any information contained in this answer is not intended to be treated as legal advice. It is for informational purposes to educate about legal issues. You should contact an attorney for specific legal advice for your situation. Specific legal advice based on full knowledge of your specific situation and all facts may differ from general information. This posting does not create an attorney-client relationship or privilege of any kind. This attorney actively licensed only in the State of Georgia. If this is a Georgia matter, you may of course contact me to discuss possible representation. FEEDBACK: Both AVVO and other readers are interested in your feedback on the quality of the answers. Please check the “thumbs up” symbol if you find an answer helpful.