WP Import Pro Help with linking records

I’m importing a large chunk of data with the plugin WP Import Pro

I’m a little stuck and wondering if you could help me out and or point me in the right direction.

Allow me to explain.

We are using custom post types and have:

Clients Sites Users Assets Services

Each are “linked” to each other and on the front end, we have dashboards:

Clients Sites Users Assets

A client dashboard with display, all sites, users, assets and services associated with said client. This is inputted into the system via a variety of Ninja Forms.

However. What I can’t figure out is how to link them in the WP ALL Import tool.

I can import a client and am making the identifier {client[1]} this makes the site and gives and id.

However, when trying to make a site. It imports the data and I’ve tried putting {client[1]} in the custom fields and with the identifier as {client[1]} but this doesn’t seem to be linking the records.

I have also tried not putting the {client[1]} field in and setting the identifier as {site[1]}

Any help / point in the right direction you can give me, would be most appreciated