Conditional Taxonomies based on Make & Model

I have been trying to implement a few conditional taxonomies based on the Make and Model fields that are currently included with the car dealer theme. I’ve run into a few snags that are preventing me from getting the desired result. I have reviewed the video instructions for Linking Taxonomy Fields ( https://youtu.be/qgnEnoltrvM ) but it seems that some things have changed since the video was created. In the video the “Make” and “Model” fields are custom taxonomies which the presenter created through the general settings. In the theme I’ve installed, these fields already exist. I am not able to use the Make or Model as a parent of my custom taxonomies. I assume that these must be hard coded in the theme somewhere, and so they are not set up as taxonomies themselves. A workaround is to recreate them as custom taxonomies, which I did, however now they appear both at the top and the bottom of the listing creation form, again I assume because they are hard coded somewhere. So my questions are these:

1. How do I remove the default “Make” and “Model” fields/taxonomies from the theme.
2. How do I rearrange the display order of the custom fields so that they make more sense? The “Display Order” field of the custom fields does not seem to work.

Any help would be greatly appreciated. Thank you