Advanced Search Category Filter

Hello,

I have used three tiers of categories (eg. Accommodation > Caravan Park (CP) > CP – Pet Friendly) to allow users to distinguish whether they are for example pet friendly. This way they can be filtered directly on the map.
I understand this is not the traditional way of doing this as I haven’t used custom fields.
I currently have the advanced search filter set up to allow users to check multiple categories from a list, but as you can imagine the list is rather long.
Not Sure if this is possible but can I somehow split the list at the second tier category (eg. Caravan Park (CP)) and display it in columns??
Or even better have some sort of expanding list similar to the one displayed directly on the map or your location swither such as this

This is my Site

Thankyou