Today, I came across a facebook account with the first name “Leonimama”: presumably, to provide some anonymity and non-searchability while remaining recogniseable to her friends who know that she has a daughter called Leonie.
It reminded me of Arabic kunyas where people will be referred to as the father/daughter of their eldest child (for example, Umm Khalid, a user in our local Freecycle group, or Abu Mazen, as Mahmoud Abbas is sometimes known).
I’m not sure I had seen a German teknonym in print before this, though :)
(Though certainly heard of it: when parents of children who attend the same kindergarten/school/daycare/etc. speak with each other, I’ve heard them introduce themselves as “Ich bin die Mutter von Leonie”: where the parents will be familiar with the other child’s name from their own child’s reports of their day or from a class list, or where they may even know the other child—but not the parent.)