First, you need to get an experienced Topographer and Attorney to give you a correct answers for your area. Where I live, the minimum lot size for a farm that does not have public road frontage is 5000 square meters. You should hire a Topographer to visit your site and work with him to decide the boundries of your lots. Once you have a general idea of the property lines, he will take readings at different points and load them into his laptop. He will generate new "Planos" for each new lot. These new Planos will be submitted to the Catastral for initial approval and then submitted to the Municipality for a Visado. Once you have these two approvals, it will be submitted to the Registro Nacional to record the subdivision. Your Topographer and Attorney can work to get this all done. It could cost anywhere from $2000 to $5000, depending on the rates of the Topographer and Attorney. Don't pay all until the registered Planos are returned to you. It will take at least 3 months or more. Make sure you get a "Uso de Suelo" (Use of Terrain) from the Municipality, ensuring your right to build on the property. Each lot will need to have access via a Servidumbre from the entrance of the property. Good luck.