Hello William,
I found in the bibliothek of the SHFam:
Köl(l)n/Kölling/: 070; 806; 807; 918;
1014; 1277
In these bookletts you can find something of the Kölln-family. But not shure to find your
Wilhelm Kölln and Mathias Kölln from Elmshorn.
Now it will last a long time to go there for getting informations.
If you have time, please wait.
Another posibility is to ask in other mailing-lists.
I will do it.
Regrards
Klaus Riecken
Kassenwart der Schleswig-Holsteinischen Familienforschung e.V.