Add functionality to an existing driectory

We are working on a directory website. We purchased a plugin and need some additional functionality added to it. We are looking to add a functionality that will allow the directory to be sorted by tags. It would work like [login to view URL] where the people will pick their main category, then they will see check boxes listing the tags. When they click a tag it will display listings that have that tag. The directory plugin we are using is Sabai