2 custom post types

I have 2 custom post types: broker and car.

It’s should be only possible to go to the single car page if you’ve selected a broker.

I can go to safelease.test/broker/broker-name and I can go to safelease.test/car/car-name

If I go to the broker detail page, the broker’s information is saved in a session. If I click through to the a car detail page, I can fill in the form at the bottom that contacts that specific broker.

The issue at the moment is, If I go directly to safelease.test/car/car-name no broker is selected. So someone on Stackoverflow suggested me to use this plugin so that my URL could be safelease.test/broker/broker-name/car/car-name.

I’ve tried multiple settings but none of them seem to work.
For example.
RegularExpression: ^broker/([a-zA-z]+)?/car/([a-zA-z]+)?
SelectType: Custom Post type (car)

Can someone help me with this?

Thanks in advance.