A client is looking to basically have a set of subcategories that are children of every category (not just one).
For example, the categories are Car, Home, Personal, Property and Travel.
Subcategories would be Insurance, Safety and Care, and each one would live in each Category. Permalinks will include /car/insurance, /car/safety, /home/insurance, /home/safety, etc. Note the subcategory slugs are the same, which is not the case with typical subcategories.
Any ideas on how to achieve this? I was thinking about using tags instead of subcategories but I don't see a way to add a tag to a permalink URL.