I need help with the REST API pipe - save to connection field

I have 3 tables:
Table 1: users
Table 2: employees
Table 3: additional data about employees.

Table 2 has a connection to the users table
Table 3 has a connection to the users and to the employees tables

My goal: I create a user in a form and immediate also create the records connected to this user in Table 2 and table 3. But in table 3 I want to set an additional connection to ermployees table.

With table rules I can make connections to the users table easily, but for the connection between table 2 and table 3 I need a pipe to do that (according to Tim).

I have limited knowledge about pipes, therefore I watched a course on API’s on Youtube. I have used CURL to understand it, but I think not enough. I checked the whole forum, but could not find something which could help.

This is what I have, looking also in debug mode. I clearly have no clue what I am doing:

Can someone help out here:
Could you explain which table the table-id is from (table 2 or 3)
what about the Record ID
What about the field ID.
Is the 4th parameter Connection ID needed?

So this one should make the connection to the employee table (2) in the 3rd table.,

Thanks in advance for the help.