Changing Content of Drop-down Menu

I’m implementing a project on the Real Estate Pro theme from FrogThemes. There is a custom post type called “listings” that is basically a big form for putting in all the information about a property listing. There is a drop-down field for “Number of Bathrooms” that only provides whole numbers as options. Lots of homes have half-baths so I need to add 1.5, 2.5, 3.5 to the drop-down field options, or just make the field a fee-form text field. I believe this is being done with javascript, and it looks like it’s related to a “meta-box”, which I’m not familiar with. I know what the code change should be, I just don’t know how to get to the code to change it. I’m using a child theme, and I’m proficient at css and php. I just need help knowing how to go about physically navigating to this code to make the very simple change. I should have support on this from FrogThemes, but they’ve been no help. I entered a ticket with them explaining the situation and their response was “the recommended approach is to add the needed values to the drop-down field.”