With a slight modification to your DB structure you can let Ninox automagically show you the links.

Whenever you find yourself creating field names with the same name but with a number at the end then you should consider creating a subtable, like I did called Platz. I made Platz a child of Termine because a record in Platz wouldn't exist without first a record in Termine. Now a Termine can have as few as 1 Platz or an infinite amount.

So you will see in the Personen table there are two tables. The Platz table is the reference table. While the view element uses code to get the same data:

let t := this;
select Termine where number(Platz1) = t or number(Platz2) = t or number(Platz3) = t

As you can see it is very clumsy to have to search through three different fields to match the current person you are on. If you wanted a view element based on Platz the search would change to:

let t := this;
select Platz where Personen = t

Much simplier.