it's magnificent Hans! is it an Asclepiadaceae?
From this family, I have already managed to force self-pollination on the genus Stapelia and Orbea. The pollinia are hidden under the crown, which is very difficult to remove as you practically have to break off one of the pieces around the crown.
on the other hand, once fertilised, the flower fades more quickly... perhaps try it when you see that the flower is coming to the end.
