Hi Michael,
i took the time and started with the next part out of a series i have to do, and applied carefully your instructions,
down to the controlpoint level. I even had the reconstruct command run over the surface, i use as projection target for flow




Following your instructions and clicking the upper right corner and the corrosponding spot on the surface to project on, i get this result:



No matter which spot I click, i get a very similar result all the time.
If i reorient my source object (the one which i want to do the flow) the results vary and sometimes get closer to the desired result, but
always not entitely. As example please see this:



I will add the file in the next post.
Best regards
Heiner