@Mike Pratt, I’ve tried the honey approach in the past. I’m not even counting on responses anymore. I post my attempts here to keep track of what I’m doing and hopefully in the end the thread becomes useful for others in my situation.
@DJPaul, thanks for the additional clue. I think I need to go back to that “flowchart of registration events in wpmu” and get a better insight what happens where in the process.