Adaptation of PHP script for multi-lingual input

I have been trying to modify an existing PHP based software that was purchased for a real-estate based business to make it support input of more than one language at a time (which currently is not supported). The software is known as PropertyMax Pro and I have been successful in making it accept input for 2 out of 3 of the types of fields required. I have run into a problem where I should be able to select features from a list of check-boxes in multiple languages and then store them in the database to be retrieved on the main website later. I can make the check-boxes I need in other languages and create the back-end structure in MySQL with the appropriate sets of features but cannot work out how to populate the database with the information from the check-boxes. I am no PHP pro and can manage simple edits only. This project requires only the editing of a single php file and needs to be done fairly quickly. Thank-you for your interest