Widget Problem: Child Widget Alignment

Hi, I have a tricky problem:

I have an overlay in a widget where I want to add a child.
This child is another widget. The logic itself works wonderfully,
the child is added and removed.


Now the problem:

If the child widget is created and added to the overlay,
it will not be fully aligned. The alignment is at the default setting (top-left alignment).

But I want it to be aligned that way (when it gets added as child):

What do I overlook? I already tried to set the alignment via blueprints, which does not work.

Question: Is it possible to control the alignment differently than manually?

In Blueprints.

I would appreciate an answer.