Thanks Richard.

I have some problems to 'see' how to implement the creation of records.

Right now it starts in the Contact table.
The scripts sets the needed keys in a variable (formal global), goes to the
vehicle table, creates a new record and set the zkf_customerID.
The address fields are related fields based on the customerID.
(or would look ups be better?).

If I put a join table in the middle, I can not link the customer to the
vehicle in one move.
So, a button on the vehicle layout should cover that.

That would be for the first 'owner'.
A date field and a 'new owner' field on the vehicle layout, with a re-assign
button should cover the switch in owners by creating a new record in the
join table with dateStart and ID of new owner, while the dateStart should be
set in the dateEnd record of the 'previous' user.

I'm I close or is there a less complicated method.

I'm open for suggestion, willing to learn, because now I know enough from FM
to be dangerous.