You need to contact your City or Town Planning Department to find out what the zoning regulations allow. Some towns or cities require that buildable lots are a certain size. For example, I just sold some land here in Olive Branch, Mississippi and the City of Olive Branch requires that to build a home you must have at least two acres of land. The property was 3 acres and the new buyer is now able to build a home otherwise I could not have allowed this property to be sold as a lot to build a home.
Another document you need to obtain is the plan of land or plat to see where the boundaries are and also obtain the deed to see if any restrictions or reservations are listed on the Deed. I would contact a real estate attorney to assist you with this transaction due to the legal documents you will need to convey your interest into separate lots.